# 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 given list.

Examples:

```Input : list1 = [10, 20, 4]
Output : 10

Input : list2 = [70, 11, 20, 4, 100]
Output : 70```

Method 1: Sorting is an easier but less optimal method. Given below is an O(n) algorithm to do the same.

 `# 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``] ` ` `  `max``=``max``(list1[``0``],list1[``1``]) ` `secondmax``=``min``(list1[``0``],list1[``1``]) ` ` `  `for` `i ``in` `range``(``2``,``len``(list1)): ` `    ``if` `list1[i]>``max``: ` `        ``secondmax``=``max` `        ``max``=``list1[i] ` `    ``else``: ` `        ``if` `list1[i]>secondmax: ` `            ``secondmax``=``list1[i] ` ` `  `print``(``"Second highest number is : "``,``str``(secondmax)) `

Method 2 : Sort the list in ascending order and print the second last element in the list.

 `# 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``]) `

Output:

`Largest element is: 45`

Method 3 : By removing the max element from list

 `# 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)) `

Output:

`Largest element is: 45`

Method 3 : Find max list element on inputs provided by user

 `# 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``]) `

Output:

```Enter number of elements in list: 4
Enter elements: 12
Enter elements: 19
Enter elements: 1
Enter elements: 99
Largest element is: 19```

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