﻿ Python: Find the second largest number in a list - w3resource

# Python: Find the second largest number in a list

## Python List: Exercise - 28 with Solution

Write a Python program to find the second largest number in a list.

Example - 1 :

Example - 2 :

Example - 3 :

Example - 4 :

Sample Solution:

Python Code:

``````# Define a function named 'second_largest' that takes a list of numbers 'numbers' as a parameter
def second_largest(numbers):
# Check if the length of the 'numbers' list is less than 2; return None in this case
if len(numbers) < 2:
return

# Check if there are only two elements in the 'numbers' list, and they are the same; return None in this case
if len(numbers) == 2 and numbers[0] == numbers[1]:
return

# Create an empty set 'dup_items' to store duplicate items and an empty list 'uniq_items' to store unique items
dup_items = set()
uniq_items = []

# Iterate through the elements in the 'numbers' list
for x in numbers:
# Check if 'x' is not in 'dup_items'; if not, add it to 'uniq_items' and 'dup_items'
if x not in dup_items:
uniq_items.append(x)

# Sort the 'uniq_items' list in ascending order
uniq_items.sort()

# Return the second largest item from the sorted 'uniq_items' list, which is at index -2 (second from the end)
return uniq_items[-2]

# Call the 'second_largest' function with different lists and print the results
print(second_largest([1, 2, 3, 4, 4]))
print(second_largest([1, 1, 1, 0, 0, 0, 2, -2, -2]))
print(second_largest([2, 2]))  # Edge case with two identical elements, returns None
print(second_largest([1]))  # Edge case with a single element, returns None
```
```

Sample Output:

```3
1
None
None
```

Flowchart:

Python Code Editor:

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