Python program to find second largest number in a list
Given a list of numbers, the task is to write a Python program to find the second largest number in the given list.
Examples:
Method 1: Sorting is an easier but less optimal method. Given below is an O[n] algorithm to do the same.
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# Python program to find second largest
# number in a list
# list of numbers - length of
# list should be at least 2
list1 = [10, 20, 4, 45, 99]
mx=max[list1[0],list1[1]]
secondmax=min[list1[0],list1[1]]
n =len[list1]
for i in range[2,n]:
if list1[i]>mx:
secondmax=mx
mx=list1[i]
elif list1[i]>secondmax and \
mx != list1[i]:
secondmax=list1[i]
print["Second highest number is : ",\
str[secondmax]]
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Method 2: Sort the list in ascending order and print the second last element in the list.
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# Python program to find largest
# number in a list
# list of numbers
list1 = [10, 20, 4, 45, 99]
# sorting the list
list1.sort[]
# printing the second last element
print["Second largest element is:", list1[-2]]
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Second largest element is: 45
Method 3: By removing the max element from the list
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# Python program to find second largest
# number in a list
# list of numbers
list1 = [10, 20, 4, 45, 99]
# new_list is a set of list1
new_list = set[list1]
# removing the largest element from temp list
new_list.remove[max[new_list]]
# elements in original list are not changed
# print[list1]
print[max[new_list]]
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Method 4: Find max list element on inputs provided by the user
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# Python program to find second largest
# number in a list
# creating empty list
list1 = []
# asking number of elements to put in list
num = int[input["Enter number of elements in list: "]]
# iterating till num to append elements in list
for i in range[1, num + 1]:
ele = int[input["Enter elements: "]]
list1.append[ele]
'''
# sort the list
list1.sort[]
# print second maximum element
print["Second largest element is:", list1[-2]]
'''
# print second maximum element using sorted[] method
print["Second largest element is:", sorted[list1][-2]]
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Output:
Enter number of elements in list: 4 Enter elements: 12 Enter elements: 19 Enter elements: 1 Enter elements: 99 Second Largest element is: 19Method 5: Traverse once to find the largest and then once again to find the second largest.
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def findLargest[arr]:
secondLargest = arr[0]
largest = arr[0]
for i in range[len[arr]]:
if arr[i] > largest:
largest = arr[i]
for i in range[len[arr]]:
if arr[i] > secondLargest and arr[i] != largest:
secondLargest = arr[i]
return secondLargest
print[findLargest[[10, 20, 4, 45, 99]]]
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Output:
45Python program to find second largest number in a list
In this tutorial, we will write a Python program to find the second largest number in a list. List is an ordered set of values enclosed in square brackets [ ]. List stores some values called elements in it, which can be accessed by their particular index. We will be following various approaches to find the second largest number in a list.
For a given list of numbers, the task is to find the largest number in the list.
Input: [11, 5, 2, 8, 4, 19]
Output: 11
Input: [2, 11, 18, 23, 6]
Output: 18
Python Program to Find Second Largest Number in List
This article is created to cover some programs in Python, that find and prints second largest number or element in a given list. Here are the list of programs covered in this article:
- Find Second Largest Number in a List of 10 elements using for Loop
- Find Second Largest Number in a List of N elements using for Loop
- Find Second Largest Number in a List of given Size using max[] Method
Second Largest Number in Python
When we have a lot of elements in our list, the thought of finding the highest or lowest element can come to our mind and Python has made it much easier for us.
In this article, we shall how we can use to find the second largest number in Python from a list.
- Sorting the list and then print the second last number.
- Removing the maximum element.
- Finding the maximum element.
- Traversing the list.
Let us have a look at the first approach-
Python Program to find Second Largest Number in a List Example 1
This python programallows user to enter the length. Next, we used For Loop to add numbers to the list in Python.
The sort function in python sorts the List elements in ascending order. Next, we are using the Python Index position to print Last but one element in a List.
NumList = [] Number = int[input["Please enter the Total Number of List Elements: "]] for i in range[1, Number + 1]: value = int[input["Please enter the Value of %d Element : " %i]] NumList.append[value] NumList.sort[] print["The Largest Element in this List is : ", NumList[Number - 2]]