Как найти второй максимальный элемент массива python

Можете просто примерно написать как думать, а то вообще идей нет

Total Pusher's user avatar

задан 6 окт 2019 в 6:26

Forer's user avatar

2

first_max = int(input())
second_max = int(input())
if first_max < second_max:
    first_max, second_max = second_max, first_max
element = int(input())
while element != 0:
    if element > first_max:
        second_max, first_max = first_max, element
    elif element > second_max:
        second_max = element
    element = int(input())
print(second_max)

ответ дан 6 окт 2019 в 6:27

Андрей Крузлик's user avatar

Андрей КрузликАндрей Крузлик

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Пожалуй эффективнее всего будет воспользоваться функцией heapq.nlargest():

from heapq import nlargest

res = nlargest(2, items)[1]

ответ дан 6 окт 2019 в 7:14

MaxU - stand with Ukraine's user avatar

Можно написать функцию:

def find_maxes(array, count):
    # копируем список чтобы не изменить старую
    copied_array = array.copy()
    maximums = []
    if count > len(copied_array):
        raise ValueError('Количество не может превышать длину списка')
    for _ in range(count):
        max_val = max(copied_array)  # получаем максимальное значение
        copied_array.remove(copied_array)  # удаляем его из списка
        maximums.append(max_val)  # добавляем в наш ожидаемый результат
    return maximums

или же можно поступить хитро

def find_maxes(array, count):
    if count > len(array):
        raise ValueError('Количество не может превышать длину списка')
    sorted_array = sorted(array)  # отсортировать список
    # Забрать последние элементы из спика так как они будут максимальными
    return sorted_array[len(array)-count: len(array)]

ответ дан 6 окт 2019 в 6:44

E1mir's user avatar

E1mirE1mir

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2

b=[3,5,6,7,7,7]

print(list(set(b))[-2])

функция set позволит создать множество отсортированных по возрастанию отличных друг от друга чисел, функция list позволит создать список и обратиться к предпоследнему (или -2) элементу.

<<6

ответ дан 29 окт 2020 в 21:37

FeToR's user avatar

FeToRFeToR

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Когда в списке много элементов, нам может понадобиться найти максимальный или минимальный элемент, и Python значительно упростил нам задачу.

В этой статье мы расскажем, как можно найти второе по величине число в списке Python с помощью следующих принципов:

  1. Сортировка списка и печать предпоследнего числа списка.
  2. Удаление максимального элемента.
  3. Нахождение максимального элемента.
  4. Перемещение по списку.

Давайте разберем первый подход.

Сортировка списка и печать предпоследнего числа

Следующая программа показывает, как это можно сделать на Python.

Пример –

 
#program to find the second largest number of list 
# declaring the list 
list_val = [20, 30, 40, 25, 10] 
# sorting the list 
list_val.sort() 
#displaying the second last element of the list 
print("The second largest element of the list is:", list_val[-2]) 

Выход:

The second largest element of the list is: 30 

Объяснение –

  1. Мы объявили список, из которого хотим изъять второй элемент, начиная с конца списка.
  2. После этого мы использовали метод сортировки, чтобы все элементы нашего списка располагались в порядке возрастания.
  3. Теперь мы используем отрицательную индексацию, так как второе по величине число будет на предпоследней позиции.

Второй метод – получить второй по величине элемент списка, удалив максимальный элемент.

Давайте посмотрим, как мы можем это сделать.

Удаление максимального элемента

Пример –

 
#program to find the second largest number of list 
 
# declaring the list 
list_val = [20, 30, 40, 25, 10] 
 
# new_list is a set of list1 
res_list = set(list_val) 
 
#removing the maximum element 
res_list.remove(max(res_list)) 
 
#printing the second largest element  
print(max(res_list)) 

Выход:

30 

Объяснение –

Давайте разберемся, что мы сделали в вышеуказанной программе:

  1. Мы объявили список, из которого хотим изъять второй по величине элемент.
  2. После этого мы использовали метод set, чтобы взять все уникальные элементы списка.
  3. Теперь мы используем max(), чтобы получить максимальное значение из списка, а затем удаляем его.
  4. После этого мы печатаем максимум результирующего списка, который даст нам второе по величине число.

В третьем методе мы будем использовать цикл for и и с его помощью найдем второй максимум из списка.

Нахождение максимального элемента

Пример –

 
# declaring empty list 
list_val = [] 
 
# user provides the number of elements to be added in the list 
num_list = int(input("Enter number of elements in list: ")) 
 
 
for i in range(1, num_list + 1): 
 element = int(input("Enter the elements: ")) 
 list_val.append(element) 
 
 
# sort the list 
list_val.sort() 
 
# print second largest element 
print("Second largest element is:", list_val[-2]) 

Выход:

Enter number of elements in list: 5 
 
Enter the elements: 10 
 
Enter the elements: 20 
 
Enter the elements: 30 
 
Enter the elements: 40 
 
Enter the elements: 50 
The second largest element is: 40 

Объяснение –

  1. Мы объявили пустой список, в который будем вставлять элементы.
  2. После этого мы просим пользователя предоставить нам количество элементов, которые мы хотели бы добавить в наш список.
  3. Используем метод сортировки, чтобы все элементы нашего списка располагались в порядке возрастания.
  4. Теперь мы применим отрицательную индексацию, так как второе по величине число будет на второй последней позиции.

Перемещение по списку

В последней программе мы пройдемся по списку, чтобы найти наибольшее число, а затем с помощью условных операторов найдем второе по величине число в списке.

Следующая программа это проиллюстрирует:

 
def calc_largest(arr): 
 second_largest = arr[0] 
 largest_val = arr[0] 
 for i in range(len(arr)): 
 if arr[i] > largest_val: 
 largest_val = arr[i] 
 
 for i in range(len(arr)): 
 if arr[i] > second_largest and arr[i] != largest_val: 
 second_largest = arr[i] 
 
 return second_largest 
print(calc_largest([20, 30, 40, 25, 10])) 

Выход:

30 

Объяснение –

Давайте разберемся, что мы сделали в вышеуказанной программе:

  1. Первый шаг – создать функцию, которая проверяет наибольшее число из списка, просматривая его.
  2. В следующем цикле for мы снова просматриваем список для поиска наибольшего числа, но на этот раз исключаем предыдущий, так как здесь наша цель – найти вторую по величине функцию.
  3. Наконец, мы передаем наш список в функцию.

Итак, в этой статье у нас была возможность подумать нестандартно и открыть для себя несколько новых способов разработки логики поиска второго по величине числа в Python.

Изучаю Python вместе с вами, читаю, собираю и записываю информацию опытных программистов.

I’m learning Python and the simple ways to handle lists is presented as an advantage. Sometimes it is, but look at this:

>>> numbers = [20,67,3,2.6,7,74,2.8,90.8,52.8,4,3,2,5,7]
>>> numbers.remove(max(numbers))
>>> max(numbers)
74

A very easy, quick way of obtaining the second largest number from a list. Except that the easy list processing helps write a program that runs through the list twice over, to find the largest and then the 2nd largest. It’s also destructive – I need two copies of the data if I wanted to keep the original. We need:

>>> numbers = [20,67,3,2.6,7,74,2.8,90.8,52.8,4,3,2,5,7]
>>> if numbers[0]>numbers[1]):
...    m, m2 = numbers[0], numbers[1]
... else:
...    m, m2 = numbers[1], numbers[0]
...
>>> for x in numbers[2:]:
...    if x>m2:
...       if x>m:
...          m2, m = m, x
...       else:
...          m2 = x
...
>>> m2
74

Which runs through the list just once, but isn’t terse and clear like the previous solution.

So: is there a way, in cases like this, to have both? The clarity of the first version, but the single run through of the second?

asked Apr 25, 2013 at 22:16

boisvert's user avatar

10

You could use the heapq module:

>>> el = [20,67,3,2.6,7,74,2.8,90.8,52.8,4,3,2,5,7]
>>> import heapq
>>> heapq.nlargest(2, el)
[90.8, 74]

And go from there…

Natan Streppel's user avatar

answered Apr 25, 2013 at 22:23

Jon Clements's user avatar

Jon ClementsJon Clements

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11

Since @OscarLopez and I have different opinions on what the second largest means, I’ll post the code according to my interpretation and in line with the first algorithm provided by the questioner.

def second_largest(numbers):
    count = 0
    m1 = m2 = float('-inf')
    for x in numbers:
        count += 1
        if x > m2:
            if x >= m1:
                m1, m2 = x, m1            
            else:
                m2 = x
    return m2 if count >= 2 else None

(Note: Negative infinity is used here instead of None since None has different sorting behavior in Python 2 and 3 – see Python – Find second smallest number; a check for the number of elements in numbers makes sure that negative infinity won’t be returned when the actual answer is undefined.)

If the maximum occurs multiple times, it may be the second largest as well. Another thing about this approach is that it works correctly if there are less than two elements; then there is no second largest.

Running the same tests:

second_largest([20,67,3,2.6,7,74,2.8,90.8,52.8,4,3,2,5,7])
=> 74
second_largest([1,1,1,1,1,2])
=> 1
second_largest([2,2,2,2,2,1])
=> 2
second_largest([10,7,10])
=> 10
second_largest([1,1,1,1,1,1])
=> 1
second_largest([1])
=> None
second_largest([])
=> None

Update

I restructured the conditionals to drastically improve performance; almost by a 100% in my testing on random numbers. The reason for this is that in the original version, the elif was always evaluated in the likely event that the next number is not the largest in the list. In other words, for practically every number in the list, two comparisons were made, whereas one comparison mostly suffices – if the number is not larger than the second largest, it’s not larger than the largest either.

answered Apr 25, 2013 at 23:15

Thijs van Dien's user avatar

Thijs van DienThijs van Dien

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12

You could always use sorted

>>> sorted(numbers)[-2]
74

answered Apr 25, 2013 at 22:21

Volatility's user avatar

VolatilityVolatility

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1

Try the solution below, it’s O(n) and it will store and return the second greatest number in the second variable. UPDATE: I’ve adjusted the code to work with Python 3, because now arithmetic comparisons against None are invalid.

Notice that if all elements in numbers are equal, or if numbers is empty or if it contains a single element, the variable second will end up with a value of None – this is correct, as in those cases there isn’t a “second greatest” element.

Beware: this finds the “second maximum” value, if there’s more than one value that is “first maximum”, they will all be treated as the same maximum – in my definition, in a list such as this: [10, 7, 10] the correct answer is 7.

def second_largest(numbers):
    minimum = float('-inf')
    first, second = minimum, minimum
    for n in numbers:
        if n > first:
            first, second = n, first
        elif first > n > second:
            second = n
    return second if second != minimum else None

Here are some tests:

second_largest([20, 67, 3, 2.6, 7, 74, 2.8, 90.8, 52.8, 4, 3, 2, 5, 7])
=> 74
second_largest([1, 1, 1, 1, 1, 2])
=> 1
second_largest([2, 2, 2, 2, 2, 1])
=> 1
second_largest([10, 7, 10])
=> 7
second_largest( [1, 3, 10, 16])
=> 10
second_largest([1, 1, 1, 1, 1, 1])
=> None
second_largest([1])
=> None
second_largest([])
=> None

answered Apr 25, 2013 at 22:51

Óscar López's user avatar

Óscar LópezÓscar López

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13

You can find the 2nd largest by any of the following ways:

Option 1:

numbers = set(numbers)
numbers.remove(max(numbers))
max(numbers)

Option 2:

sorted(set(numbers))[-2]

answered Jul 12, 2018 at 16:12

Sahil Chhabra's user avatar

Sahil ChhabraSahil Chhabra

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0

The quickselect algorithm, O(n) cousin to quicksort, will do what you want. Quickselect has average performance O(n). Worst case performance is O(n^2) just like quicksort but that’s rare, and modifications to quickselect reduce the worst case performance to O(n).

The idea of quickselect is to use the same pivot, lower, higher idea of quicksort, but to then ignore the lower part and to further order just the higher part.

answered Jun 13, 2015 at 18:36

Edward Doolittle's user avatar

Edward DoolittleEdward Doolittle

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2

Why to complicate the scenario? Its very simple and straight forward

  1. Convert list to set – removes duplicates
  2. Convert set to list again – which gives list in ascending order

Here is a code

mlist = [2, 3, 6, 6, 5]
mlist = list(set(mlist))
print mlist[-2]

answered Nov 7, 2016 at 7:36

Abhishek Kulkarni's user avatar

3

This is one of the Simple Way

def find_second_largest(arr):
    first, second = float('-inf'), float('-inf')

    for number in arr:
        if number > first:
            second = first
            first = number
        elif second < number < first:
            second = number

    return second

answered Oct 19, 2021 at 11:58

Ganesh Patil's user avatar

2

there are some good answers here for type([]), in case someone needed the same thing on a type({}) here it is,

def secondLargest(D):
    def second_largest(L):  
        if(len(L)<2):
            raise Exception("Second_Of_One")
        KFL=None #KeyForLargest
        KFS=None #KeyForSecondLargest
        n = 0
        for k in L:
            if(KFL == None or k>=L[KFL]):
                KFS = KFL
                KFL = n
            elif(KFS == None or k>=L[KFS]):
                KFS = n
            n+=1
        return (KFS)
    KFL=None #KeyForLargest
    KFS=None #KeyForSecondLargest
    if(len(D)<2):
        raise Exception("Second_Of_One")
    if(type(D)!=type({})):
        if(type(D)==type([])):
            return(second_largest(D))
        else:
            raise Exception("TypeError")
    else:
        for k in D:
            if(KFL == None or D[k]>=D[KFL]):
                KFS = KFL               
                KFL = k
            elif(KFS == None or D[k] >= D[KFS]):
                KFS = k
    return(KFS)

a = {'one':1 , 'two': 2 , 'thirty':30}
b = [30,1,2] 
print(a[secondLargest(a)])
print(b[secondLargest(b)])

Just for fun I tried to make it user friendly xD

answered Jan 13, 2015 at 16:24

kpie's user avatar

kpiekpie

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O(n): Time Complexity of a loop is considered as O(n) if the loop variables is incremented / decremented by a constant amount. For example following functions have O(n) time complexity.

 // Here c is a positive integer constant   
   for (int i = 1; i <= n; i += c) {  
        // some O(1) expressions
   }

To find the second largest number i used the below method to find the largest number first and then search the list if thats in there or not

x = [1,2,3]
A = list(map(int, x))
y = max(A)
k1 = list()
for values in range(len(A)):
if y !=A[values]:
    k.append(A[values])

z = max(k1)
print z

answered Aug 2, 2016 at 6:27

Bharatwaja's user avatar

BharatwajaBharatwaja

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    def SecondLargest(x):
        largest = max(x[0],x[1])
        largest2 = min(x[0],x[1])
        for item in x:
            if item > largest:
               largest2 = largest
               largest = item
            elif largest2 < item and item < largest:
               largest2 = item
        return largest2
    SecondLargest([20,67,3,2.6,7,74,2.8,90.8,52.8,4,3,2,5,7])

answered Apr 30, 2018 at 22:33

Mike's user avatar

MikeMike

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Just to make the accepted answer more general, the following is the extension to get the kth largest value:

def kth_largest(numbers, k):
    largest_ladder = [float('-inf')] * k
    count = 0
    for x in numbers:
        count += 1
        ladder_pos = 1
        for v in largest_ladder:
            if x > v:
                ladder_pos += 1
            else:
                break
        if ladder_pos > 1:
            largest_ladder = largest_ladder[1:ladder_pos] + [x] + largest_ladder[ladder_pos:]
    return largest_ladder[0] if count >= k else None

answered Jan 9, 2019 at 5:39

Bily's user avatar

BilyBily

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list_nums = [1, 2, 6, 6, 5]
minimum = float('-inf')
max, min = minimum, minimum
for num in list_nums:
    if num > max:
        max, min = num, max
    elif max > num > min:
        min = num
print(min if min != minimum else None)

Output

5

answered May 12, 2020 at 12:55

Shivam Bharadwaj's user avatar

Using reduce from functools should be a linear-time functional-style alternative:

from functools import reduce

def update_largest_two(largest_two, x):
    m1, m2 = largest_two
    return (m1, m2) if m2 >= x else (m1, x) if m1 >= x else (x, m1)


def second_largest(numbers):
    if len(numbers) < 2:
        return None
    largest_two = sorted(numbers[:2], reverse=True)
    rest = numbers[2:]
    m1, m2 = reduce(update_largest_two, rest, largest_two)
    return m2

… or in a very concise style:

from functools import reduce

def second_largest(n):
    update_largest_two = lambda a, x: a if a[1] >= x else (a[0], x) if a[0] >= x else (x, a[0])

    return None if len(n) < 2 else (reduce(update_largest_two, n[2:], sorted(n[:2], reverse=True)))[1]

answered Aug 17, 2022 at 13:11

Bernhard Stadler's user avatar

2

>>> l = [19, 1, 2, 3, 4, 20, 20]
>>> sorted(set(l))[-2]
19

answered Jul 21, 2015 at 22:52

Brent D.'s user avatar

Brent D.Brent D.

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This can be done in [N + log(N) – 2] time, which is slightly better than the loose upper bound of 2N (which can be thought of O(N) too).

The trick is to use binary recursive calls and “tennis tournament” algorithm. The winner (the largest number) will emerge after all the ‘matches’ (takes N-1 time), but if we record the ‘players’ of all the matches, and among them, group all the players that the winner has beaten, the second largest number will be the largest number in this group, i.e. the ‘losers’ group.

The size of this ‘losers’ group is log(N), and again, we can revoke the binary recursive calls to find the largest among the losers, which will take [log(N) – 1] time. Actually, we can just linearly scan the losers group to get the answer too, the time budget is the same.

Below is a sample python code:

def largest(L):
    global paris
    if len(L) == 1:
        return L[0]
    else:
        left = largest(L[:len(L)//2])
        right = largest(L[len(L)//2:])
        pairs.append((left, right))
        return max(left, right)

def second_largest(L):
    global pairs
    biggest = largest(L)
    second_L = [min(item) for item in pairs if biggest in item]

    return biggest, largest(second_L)  



if __name__ == "__main__":
    pairs = []
    # test array
    L = [2,-2,10,5,4,3,1,2,90,-98,53,45,23,56,432]    

    if len(L) == 0:
        first, second = None, None
    elif len(L) == 1:
        first, second = L[0], None
    else:
        first, second = second_largest(L)

    print('The largest number is: ' + str(first))
    print('The 2nd largest number is: ' + str(second))

answered Sep 29, 2016 at 5:47

ccy's user avatar

ccyccy

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1

Objective: To find the second largest number from input.

Input : 5
2 3 6 6 5

Output: 5

*n = int(raw_input())
arr = map(int, raw_input().split())
print sorted(list(set(arr)))[-2]*

Abdul Rasheed's user avatar

answered Oct 24, 2017 at 8:14

Rakesh TS's user avatar

2

you have to compare in between new values, that’s the trick, think always in the previous (the 2nd largest) should be between the max and the previous max before, that’s the one!!!!

def secondLargest(lista):
    max_number   = 0
    prev_number  = 0

    for i in range(0, len(lista)):

        if lista[i] > max_number:
            prev_number = max_number
            max_number  = lista[i]
        elif lista[i] > prev_number and lista[i] < max_number:
            prev_number = lista[i]

    return prev_number

answered Mar 6, 2020 at 16:47

Brian Sanchez's user avatar

Brian SanchezBrian Sanchez

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Best solution that my friend Dhanush Kumar came up with:

    def second_max(numbers):
        glo_max = numbers[0]
        sec_max = float("-inf")
        for i in numbers:
            if i > glo_max:
                sec_max = glo_max
                glo_max = i
            elif sec_max < i < glo_max:
                sec_max = i
        return sec_max
    
    #print(second_max([-1,-3,-4,-5,-7]))
    
    assert second_max([-1,-3,-4,-5,-7])==-3
    assert second_max([5,3,5,1,2]) == 3
    assert second_max([1,2,3,4,5,7]) ==5
    assert second_max([-3,1,2,5,-2,3,4]) == 4
    assert second_max([-3,-2,5,-1,0]) == 0
    assert second_max([0,0,0,1,0]) == 0

Bernhard Stadler's user avatar

answered Nov 5, 2020 at 13:46

chia yongkang's user avatar

You can also try this:

>>> list=[20, 20, 19, 4, 3, 2, 1,100,200,100]
>>> sorted(set(list), key=int, reverse=True)[1]
100

answered Oct 24, 2016 at 5:54

Vikram Singh Chandel's user avatar

1

A simple way :

n=int(input())
arr = set(map(int, input().split()))
arr.remove(max(arr))
print (max(arr))

answered Dec 18, 2017 at 15:41

rashedcs's user avatar

rashedcsrashedcs

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0

use defalut sort() method to get second largest number in the list.
sort is in built method you do not need to import module for this.

lis = [11,52,63,85,14]
lis.sort()
print(lis[len(lis)-2])

answered Apr 23, 2018 at 12:20

saigopi.me's user avatar

saigopi.mesaigopi.me

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3

def secondlarget(passinput):
    passinputMax = max(passinput)  #find the maximum element from the array
    newpassinput = [i for i in passinput if i != passinputMax]  #Find the second largest element in the array
    #print (newpassinput)
    if len(newpassinput) > 0:
        return max(newpassinput) #return the second largest
    return 0
if __name__ == '__main__':
    n = int(input().strip())  # lets say 5
    passinput = list(map(int, input().rstrip().split())) # 1 2 2 3 3
    result = secondlarget(passinput) #2
    print (result) #2

answered Aug 19, 2019 at 6:58

if __name__ == '__main__':
    n = int(input())
    arr = list(map(float, input().split()))
    high = max(arr)
    secondhigh = min(arr)
    for x in arr:
        if x < high and x > secondhigh:
            secondhigh = x
    print(secondhigh)

The above code is when we are setting the elements value in the list
as per user requirements. And below code is as per the question asked

#list
numbers = [20, 67, 3 ,2.6, 7, 74, 2.8, 90.8, 52.8, 4, 3, 2, 5, 7]
#find the highest element in the list
high = max(numbers)
#find the lowest element in the list
secondhigh = min(numbers)
for x in numbers:
    '''
    find the second highest element in the list,
    it works even when there are duplicates highest element in the list.
    It runs through the entire list finding the next lowest element
    which is less then highest element but greater than lowest element in
    the list set initially. And assign that value to secondhigh variable, so 
    now this variable will have next lowest element in the list. And by end 
    of loop it will have the second highest element in the list  
    '''
    if (x<high and x>secondhigh):
        secondhigh=x
print(secondhigh)

answered Oct 2, 2019 at 8:38

Nisrin Dhoondia's user avatar

3

Max out the value by comparing each one to the max_item. In the first if, every time the value of max_item changes it gives its previous value to second_max. To tightly couple the two second if ensures the boundary

def secondmax(self, list):
    max_item = list[0]
    second_max = list[1]
    for item in list:
        if item > max_item:
            second_max =  max_item
            max_item = item
        if max_item < second_max:
            max_item = second_max
    return second_max

Trenton McKinney's user avatar

answered Dec 25, 2019 at 12:31

Ankit's user avatar

AnkitAnkit

454 bronze badges

1

Most of previous answers are correct but here is another way !

Our strategy is to create a loop with two variables first_highest and second_highest. We loop through the numbers and if our current_value is greater than the first_highest then we set second_highest to be the same as first_highest and then the second_highest to be the current number. If our current number is greater than second_highest then we set second_highest to the same as current numberenter image description here

#!/usr/bin/env python3
import sys
def find_second_highest(numbers):

    min_integer = -sys.maxsize -1
    first_highest= second_highest = min_integer
    for current_number in numbers:
        if current_number == first_highest and min_integer != second_highest:
            first_highest=current_number
        elif current_number > first_highest:
            second_highest = first_highest
            first_highest = current_number
        elif current_number > second_highest:
            second_highest = current_number
    return second_highest

print(find_second_highest([80,90,100]))
print(find_second_highest([80,80]))
print(find_second_highest([2,3,6,6,5]))

answered Nov 12, 2018 at 6:42

grepit's user avatar

grepitgrepit

20.8k6 gold badges101 silver badges81 bronze badges

1

Below code will find the max and the second max numbers without the use of max function. I assume that the input will be numeric and the numbers are separated by single space.

myList = input().split()
myList = list(map(eval,myList))


m1 = myList[0]
m2 = myList[0]

for x in myList:
    if x > m1:
        m2 = m1
        m1 = x
    elif x > m2:
        m2 = x

print ('Max Number: ',m1)
print ('2nd Max Number: ',m2)

answered Feb 6, 2021 at 17:22

Salman's user avatar

SalmanSalman

1,1965 gold badges28 silver badges59 bronze badges

2

Here I tried to come up with an answer.
2nd(Second) maximum element in a list using single loop and without using any inbuilt function.

def secondLargest(lst):
    mx = 0
    num = 0
    sec = 0
    for i in lst:
        if i > mx:
            sec = mx
            mx = i
        else:
            if i > num and num >= sec:
                sec = i
            num = i
    return sec

answered Apr 22, 2021 at 11:27

varun's user avatar

varunvarun

277 bronze badges

1

We can use 2 loop to compare and find the second largest number from list rather than removing max number from list:

def second_largest(list1):
   second_max = list1[0]
   max_nu = max(list1)

   for i in range(len(list1) -1):
       for j in range(1,len(list1)):
          if list1[i] > list1[j] and list1[i] < max_nu :
              second_max = list1[i]
          elif list1[i] < list1[j] and list1[j] < max_nu:
              second_max = list1[j]
   return second_max

l = [2, 4, 5, 6, 8, 7, 21, 20]
print(second_largest(l))

answered Nov 17, 2021 at 8:09

Aashutosh jha's user avatar

1

Skip to content

Задача «Второй максимум»

Условие

Последовательность состоит из различных натуральных чисел и завершается числом 0. Определите значение второго по величине элемента в этой последовательности. Гарантируется, что в последовательности есть хотя бы два элемента.

Решение задачи от разработчиков на Python:

Другая реализация задачи на Python:

Смотреть видео — Задача «Второй максимум» решение на Python

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Оставьте комментарий! Напишите, что думаете по поводу статьи.x

0 / 0 / 0

Регистрация: 15.04.2020

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1

15.04.2020, 21:41. Показов 15670. Ответов 6


Студворк — интернет-сервис помощи студентам

Ввести с клавиатуры массив из 5 элементов и найти два максимальных элемента массива и их номера. Помогите написать на питоне.



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DobroAlex

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15.04.2020, 21:48

2

lalala2020,

Python
1
2
3
4
a: List[int] = [int(input()) for j in range(5)]
max_1, max_2 = sorted(a)[-1], sorted(a)[-2]
print (a.index(max_1))
print (a.index(max_2))

Добавлено через 1 минуту
https://ideone.com/dLgggI



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0 / 0 / 0

Регистрация: 15.04.2020

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15.04.2020, 21:51

 [ТС]

3

А если без функции max?



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Заклинатель змей

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Сообщений: 2,412

15.04.2020, 21:55

4

lalala2020, давайте вы сначала напишите хотя бы поиск наибольшего числа без max сюда, а я потом подскажу, как найти второе наибольшее



0



lalala2020

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15.04.2020, 22:01

 [ТС]

5

Python
1
2
3
4
5
6
M = A[0]; nMax = 0
for i in range(1,N):
  if A[i] > M: 
    M = A[i]
    nMax = i
print ( "A[", nMax, "]=", M, sep = "" )



0



DobroAlex

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15.04.2020, 23:48

6

lalala2020, почти верно, только индексацию надо начинать с 0, а не с 1.
А вот так будет выглядеть поиск второго максимального:

Python
1
2
3
4
5
6
m2 = a[0]
m2_pos = 0
for j in range (0, N):
   if a[j] > m2 and a[j] < m:
      m2= a[j]
      m2_pos= j



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Эксперт Python

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16.04.2020, 12:16

7

DobroAlex, а зачем с нуля начинать, если ты нулевой элемент берешь как максимум?

Добавлено через 4 минуты
И, да это не будет работать для [10, 10, 10, 10, 1].
Ответ должен быть: [10, 10], а получится [10, 1]



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