# Second Smallest Element in a Linked List

Given a Linked list of integer data. The task is to write a program that efficiently finds the second smallest element present in the Linked List.

Examples:

```Input : List = 12 -> 35 -> 1 -> 10 -> 34 -> 1
Output : The second smallest element is 10.

Input : List = 10 -> 5 -> 10
Output : The second largest element is 10.
```

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

A Simple Solution will be to first sort the linked list in ascending order and then print the second element from the sorted linked list. The time complexity of this solution is O(nlogn).

A Better Solution is to traverse the Linked list twice. In the first traversal find the minimum element. In the second traversal find the smallest element greater than the element obtained in first traversal. The time complexity of this solution is O(n).

A more Efficient Solution can be to find the second smallest element in a single traversal.

## C++

 `// C++ program to print second smallest ` `// value in a linked list ` `#include ` `#include ` ` `  `using` `namespace` `std; ` ` `  `// A linked list node ` `struct` `Node { ` `    ``int` `data; ` `    ``struct` `Node* next; ` `}; ` ` `  `// Function to add a node at the ` `// beginning of Linked List ` `void` `push(``struct` `Node** head_ref, ``int` `new_data) ` `{ ` `    ``struct` `Node* new_node = ``new` `Node; ` `    ``new_node->data = new_data; ` `    ``new_node->next = (*head_ref); ` `    ``(*head_ref) = new_node; ` `} ` ` `  `// Function to print the second ` `// smallest element ` `void` `print2smallest(``struct` `Node* head) ` `{ ` `    ``int` `first = INT_MAX, second = INT_MAX; ` ` `  `    ``struct` `Node* temp = head; ` `    ``while` `(temp != NULL) { ` ` `  `        ``if` `(temp->data < first) { ` `            ``second = first; ` `            ``first = temp->data; ` `        ``} ` ` `  `        ``// If current node's data is in between ` `        ``// first and second then update second ` `        ``else` `if` `(temp->data < second && temp->data != first) ` `            ``second = temp->data; ` ` `  `        ``temp = temp->next; ` `    ``} ` ` `  `    ``if` `(second == INT_MAX) ` `        ``cout << ``"There is no second smallest element\n"``; ` `    ``else` `        ``cout << ``"The second smallest element is "` `<< second; ` `} ` ` `  `// Driver program to test above function ` `int` `main() ` `{ ` `    ``struct` `Node* start = NULL; ` ` `  `    ``/* The constructed linked list is:   ` `     ``12 -> 35 -> 1 -> 10 -> 34 -> 1 */` `    ``push(&start, 1); ` `    ``push(&start, 34); ` `    ``push(&start, 10); ` `    ``push(&start, 1); ` `    ``push(&start, 35); ` `    ``push(&start, 12); ` ` `  `    ``print2smallest(start); ` ` `  `    ``return` `0; ` `} `

## Java

 `// Java program to print second smallest ` `// value in a linked list ` `class` `GFG ` `{ ` ` `  `// A linked list node ` `static` `class` `Node  ` `{ ` `    ``int` `data; ` `    ``Node next; ` `}; ` ` `  `// Function to add a node at the ` `// beginning of Linked List ` `static` `Node push(Node head_ref, ``int` `new_data) ` `{ ` `    ``Node new_node = ``new` `Node(); ` `    ``new_node.data = new_data; ` `    ``new_node.next = head_ref; ` `    ``head_ref = new_node; ` `    ``return` `new_node; ` `} ` ` `  `// Function to print the second ` `// smallest element ` `static` `void` `print2smallest(Node head) ` `{ ` `    ``int` `first = Integer.MAX_VALUE,  ` `        ``second = Integer.MAX_VALUE; ` ` `  `    ``Node temp = head; ` `    ``while` `(temp != ``null``) ` `    ``{ ` ` `  `        ``if` `(temp.data < first) ` `        ``{ ` `            ``second = first; ` `            ``first = temp.data; ` `        ``} ` ` `  `        ``// If current node's data is in between ` `        ``// first and second then update second ` `        ``else` `if` `(temp.data < second && temp.data != first) ` `            ``second = temp.data; ` ` `  `        ``temp = temp.next; ` `    ``} ` ` `  `    ``if` `(second == Integer.MAX_VALUE) ` `        ``System.out.print(``"There is no second smallest element\n"``); ` `    ``else` `        ``System.out.print(``"The second smallest element is "` `+ second); ` `} ` ` `  `// Driver code ` `public` `static` `void` `main(String[] args) ` `{ ` `    ``Node start = ``null``; ` ` `  `    ``/* The constructed linked list is:  ` `    ``12.35.1.10.34.1 */` `    ``start = push(start, ``1``); ` `    ``start = push(start, ``34``); ` `    ``start = push(start, ``10``); ` `    ``start = push(start, ``1``); ` `    ``start = push(start, ``35``); ` `    ``start = push(start, ``12``); ` ` `  `    ``print2smallest(start); ` `} ` `} ` ` `  `// This code is contributed by PrinciRaj1992 `

## Python3

 `# Python3 program to print second smallest ` `# value in a linked list ` ` `  `# A linked list node ` `class` `Node : ` `    ``def` `__init__(``self``): ` `        ``self``.data ``=` `0` `        ``self``.``next` `=` `None` ` `  `# Function to add a node at the ` `# beginning of Linked List ` `def` `push(head_ref, new_data): ` ` `  `    ``new_node ``=` `Node() ` `    ``new_node.data ``=` `new_data ` `    ``new_node.``next` `=` `head_ref ` `    ``head_ref ``=` `new_node ` `    ``return` `new_node ` ` `  `# Function to print the second ` `# smallest element ` `def` `print2smallest(head): ` ` `  `    ``first ``=` `32676` `    ``second ``=` `32676` ` `  `    ``temp ``=` `head ` `    ``while` `(temp !``=` `None``): ` `     `  `        ``if` `(temp.data < first): ` `         `  `            ``second ``=` `first ` `            ``first ``=` `temp.data ` `         `  `        ``# If current node's data is in between ` `        ``# first and second then update second ` `        ``elif` `(temp.data < second ``and` `temp.data !``=` `first): ` `            ``second ``=` `temp.data ` ` `  `        ``temp ``=` `temp.``next` `     `  `    ``if` `(second ``=``=` `32676``): ` `        ``print``(``"There is no second smallest element"``) ` `    ``else``: ` `        ``print``(``"The second smallest element is "` `, second) ` ` `  `# Driver code ` ` `  `start ``=` `None` ` `  `# The constructed linked list is:  ` `# 12.35.1.10.34.1 ` `start ``=` `push(start, ``1``) ` `start ``=` `push(start, ``34``) ` `start ``=` `push(start, ``10``) ` `start ``=` `push(start, ``1``) ` `start ``=` `push(start, ``35``) ` `start ``=` `push(start, ``12``) ` ` `  `print2smallest(start) ` ` `  `# This code is contributed by Arnab Kundu `

## C#

 `// C# program to print second smallest ` `// value in a linked list ` `using` `System; ` ` `  `class` `GFG ` `{ ` ` `  `// A linked list node ` `class` `Node  ` `{ ` `    ``public` `int` `data; ` `    ``public` `Node next; ` `}; ` ` `  `// Function to add a node at the ` `// beginning of Linked List ` `static` `Node push(Node head_ref, ``int` `new_data) ` `{ ` `    ``Node new_node = ``new` `Node(); ` `    ``new_node.data = new_data; ` `    ``new_node.next = head_ref; ` `    ``head_ref = new_node; ` `    ``return` `new_node; ` `} ` ` `  `// Function to print the second ` `// smallest element ` `static` `void` `print2smallest(Node head) ` `{ ` `    ``int` `first = ``int``.MaxValue,  ` `        ``second = ``int``.MaxValue; ` ` `  `    ``Node temp = head; ` `    ``while` `(temp != ``null``) ` `    ``{ ` ` `  `        ``if` `(temp.data < first) ` `        ``{ ` `            ``second = first; ` `            ``first = temp.data; ` `        ``} ` ` `  `        ``// If current node's data is in between ` `        ``// first and second then update second ` `        ``else` `if` `(temp.data < second &&  ` `                 ``temp.data != first) ` `            ``second = temp.data; ` ` `  `        ``temp = temp.next; ` `    ``} ` ` `  `    ``if` `(second == ``int``.MaxValue) ` `        ``Console.Write(``"There is no second smallest element\n"``); ` `    ``else` `        ``Console.Write(``"The second smallest element is "` `+  ` `                                                 ``second); ` `} ` ` `  `// Driver code ` `public` `static` `void` `Main(String[] args) ` `{ ` `    ``Node start = ``null``; ` ` `  `    ``/* The constructed linked list is:  ` `    ``12 -> 35 -> 1 -> 10 -> 34 -> 1 */` `    ``start = push(start, 1); ` `    ``start = push(start, 34); ` `    ``start = push(start, 10); ` `    ``start = push(start, 1); ` `    ``start = push(start, 35); ` `    ``start = push(start, 12); ` ` `  `    ``print2smallest(start); ` `} ` `} ` ` `  `// This code is contributed by Rajput-Ji `

Output:

```The second smallest element is 10
```

Time complexity : O(n)

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