Find Second largest element in an array - GeeksforGeeks

27 Feb, 2022
Given an array of integers, our task is to write a program that efficiently finds the second largest element present in the array. Example:
Input: arr[] = {12, 35, 1, 10, 34, 1}
Output: The second largest element is 34.
Explanation: The largest element of the 
array is 35 and the second 
largest element is 34

Input: arr[] = {10, 5, 10}
Output: The second largest element is 5.
Explanation: The largest element of 
the array is 10 and the second 
largest element is 5

Input: arr[] = {10, 10, 10}
Output: The second largest does not exist.
Explanation: Largest element of the array 
is 10 there is no second largest element
Simple Solution Approach: The idea is to sort the array in descending order and then return the second element which is not equal to the largest element from the sorted array.
C++14
Java
Python3
C#
Javascript
// C++ program to find second largest// element in an array #include <bits/stdc++.h>using namespace std; /* Function to print the second largest elements */void print2largest(int arr[], int arr_size){    int i, first, second;     /* There should be atleast two elements */    if (arr_size < 2) {        printf(" Invalid Input ");        return;    }     // sort the array    sort(arr, arr + arr_size);     // start from second last element    // as the largest element is at last    for (i = arr_size - 2; i >= 0; i--) {        // if the element is not        // equal to largest element        if (arr[i] != arr[arr_size - 1]) {            printf("The second largest element is %d\n", arr[i]);            return;        }    }     printf("There is no second largest element\n");} /* Driver program to test above function */int main(){    int arr[] = { 12, 35, 1, 10, 34, 1 };    int n = sizeof(arr) / sizeof(arr[0]);    print2largest(arr, n);    return 0;}
// Java program to find second largest// element in an arrayimport java.util.*;class GFG{ // Function to print the// second largest elementsstatic void print2largest(int arr[],                          int arr_size){  int i, first, second;   // There should be  // atleast two elements  if (arr_size < 2)  {    System.out.printf(" Invalid Input ");    return;  }   // Sort the array  Arrays.sort(arr);   // Start from second last element  // as the largest element is at last  for (i = arr_size - 2; i >= 0; i--)  {    // If the element is not    // equal to largest element    if (arr[i] != arr[arr_size - 1])    {      System.out.printf("The second largest " +                        "element is %d\n", arr[i]);      return;    }  }   System.out.printf("There is no second " +                    "largest element\n");} // Driver codepublic static void main(String[] args){  int arr[] = {12, 35, 1, 10, 34, 1};  int n = arr.length;  print2largest(arr, n);}} // This code is contributed by gauravrajput1
# Python3 program to find second# largest element in an array # Function to print the# second largest elementsdef print2largest(arr,                  arr_size):    # There should be  # atleast two elements  if (arr_size < 2):      print(" Invalid Input ")    return    # Sort the array  arr.sort    # Start from second last  # element as the largest  # element is at last  for i in range(arr_size-2,                 -1, -1):      # If the element is not    # equal to largest element    if (arr[i] != arr[arr_size - 1]) :           print("The second largest element is",            arr[i])      return    print("There is no second largest element") # Driver codearr = [12, 35, 1, 10, 34, 1]n = len(arr)print2largest(arr, n) # This code is contributed by divyeshrabadiya07
// C# program to find second largest// element in an arrayusing System; class GFG{ // Function to print the// second largest elementsstatic void print2largest(int []arr,                          int arr_size){  int i;   // There should be  // atleast two elements  if (arr_size < 2)  {    Console.Write(" Invalid Input ");    return;  }   // Sort the array  Array.Sort(arr);   // Start from second last element  // as the largest element is at last  for(i = arr_size - 2; i >= 0; i--)  {           // If the element is not    // equal to largest element    if (arr[i] != arr[arr_size - 1])    {      Console.Write("The second largest " +                    "element is {0}\n", arr[i]);      return;    }  }   Console.Write("There is no second " +                "largest element\n");} // Driver codepublic static void Main(String[] args){  int []arr = { 12, 35, 1, 10, 34, 1 };  int n = arr.Length;     print2largest(arr, n);}} // This code is contributed by Amit Katiyar
<script> // Javascript program to find second largest// element in an array      // Function to print the second largest elements    function print2largest(arr, arr_size) {        let i, first, second;          // There should be atleast two elements        if (arr_size < 2) {            document.write(" Invalid Input ");            return;        }          // sort the array        arr.sort();          // start from second last element        // as the largest element is at last        for (i = arr_size - 2; i >= 0; i--) {            // if the element is not            // equal to largest element            if (arr[i] != arr[arr_size - 1]) {                document.write("The second largest element is " + arr[i]);                return;            }        }          document.write("There is no second largest element<br>");    }      // Driver program to test above function     let arr= [ 12, 35, 1, 10, 34, 1 ];    let n = arr.length;    print2largest(arr, n);      // This code is contributed by Surbhi Tyagi </script>
The second largest element is 34

Complexity Analysis:
Time Complexity: O(n log n). Time required to sort the array is O(n log n).
Auxiliary space: O(1). As no extra space is required.
Better Solution: Approach: The approach is to traverse the array twice. 
In the first traversal find the maximum element. 
In the second traversal find the greatest element in the remaining excluding the previous greatest.
C++14
Java
Python3
C#
Javascript
// C++ program to find the second largest element in the array#include <iostream>using namespace std;  int secondLargest(int arr[], int n) {    int largest = 0, secondLargest = -1;     // finding the largest element in the array    for (int i = 1; i < n; i++) {        if (arr[i] > arr[largest])            largest = i;    }     // finding the largest element in the array excluding    // the largest element calculated above    for (int i = 0; i < n; i++) {        if (arr[i] != arr[largest]) {            // first change the value of second largest            // as soon as the next element is found            if (secondLargest == -1)                secondLargest = i;            else if (arr[i] > arr[secondLargest])                secondLargest = i;        }    }    return secondLargest;}  int main() {    int arr[] = {10, 12, 20, 4};    int n = sizeof(arr)/sizeof(arr[0]);    int second_Largest = secondLargest(arr, n);    if (second_Largest == -1)        cout << "Second largest didn't exit\n";    else        cout << "Second largest : " << arr[second_Largest];}
// Java program to find second largest// element in an arrayclass GFG{ // Function to print the second largest elementsstatic void print2largest(int arr[], int arr_size){    int i, first, second;     // There should be atleast two elements    if (arr_size < 2)    {        System.out.printf(" Invalid Input ");        return;    }     int largest = second = Integer.MIN_VALUE;     // Find the largest element    for(i = 0; i < arr_size; i++)    {        largest = Math.max(largest, arr[i]);    }     // Find the second largest element    for(i = 0; i < arr_size; i++)    {        if (arr[i] != largest)            second = Math.max(second, arr[i]);    }    if (second == Integer.MIN_VALUE)        System.out.printf("There is no second " +                          "largest element\n");    else        System.out.printf("The second largest " +                          "element is %d\n", second);} // Driver codepublic static void main(String[] args){    int arr[] = { 12, 35, 1, 10, 34, 1 };    int n = arr.length;         print2largest(arr, n);}} // This code is contributed by Amit Katiyar
# Python3 program to find# second largest element# in an array # Function to print# second largest elementsdef print2largest(arr, arr_size):     # There should be atleast    # two elements    if (arr_size < 2):        print(" Invalid Input ");        return;     largest = second = -2454635434;     # Find the largest element    for i in range(0, arr_size):        largest = max(largest, arr[i]);     # Find the second largest element    for i in range(0, arr_size):        if (arr[i] != largest):            second = max(second, arr[i]);     if (second == -2454635434):        print("There is no second " +              "largest element");    else:        print("The second largest " +              "element is \n", second); # Driver codeif __name__ == '__main__':       arr = [12, 35, 1,           10, 34, 1];    n = len(arr);    print2largest(arr, n); # This code is contributed by shikhasingrajput
// C# program to find second largest// element in an arrayusing System; class GFG{ // Function to print the second largest elementsstatic void print2largest(int []arr, int arr_size){    // int first;    int i, second;     // There should be atleast two elements    if (arr_size < 2)    {        Console.Write(" Invalid Input ");        return;    }     int largest = second = int.MinValue;     // Find the largest element    for(i = 0; i < arr_size; i++)    {        largest = Math.Max(largest, arr[i]);    }     // Find the second largest element    for(i = 0; i < arr_size; i++)    {        if (arr[i] != largest)            second = Math.Max(second, arr[i]);    }         if (second == int.MinValue)        Console.Write("There is no second " +                      "largest element\n");    else        Console.Write("The second largest " +                      "element is {0}\n", second);} // Driver codepublic static void Main(String[] args){    int []arr = { 12, 35, 1, 10, 34, 1 };    int n = arr.Length;         print2largest(arr, n);}} // This code is contributed by Amit Katiyar
<script>  // Javascript program to find second largest// element in an array       // Function to print the second largest elements    function print2largest(arr, arr_size) {        let i;        let largest = second = -2454635434;           // There should be atleast two elements        if (arr_size < 2) {            document.write(" Invalid Input ");            return;        }           // finding the largest element        for (i = 0;i<arr_size;i++){            if (arr[i]>largest){                largest = arr[i];            }        }           // Now find the second largest element        for (i = 0 ;i<arr_size;i++){            if (arr[i]>second && arr[i]<largest){                second = arr[i];            }        }          if (second == -2454635434){                     document.write("There is no second largest element<br>");        }        else{            document.write("The second largest element is " + second);                return;            }        }            // Driver program to test above function      let arr= [ 12, 35, 1, 10, 34, 1 ];    let n = arr.length;    print2largest(arr, n);   </script>
Second largest : 12
Complexity Analysis:
Time Complexity: O(n). Two traversals of the array is needed.
Auxiliary space: O(1). As no extra space is required.
Efficient Solution Approach: Find the second largest element in a single traversal. Below is the complete algorithm for doing this:  
1) Initialize the first as 0(i.e, index of arr[0] element
2) Start traversing the array from array[1],
   a) If the current element in array say arr[i] is greater
      than first. Then update first and second as,
      second = first
      first = arr[i]
   b) If the current element is in between first and second,
      then update second to store the value of current variable as
      second = arr[i]
3) Return the value stored in second.
C
C++
Java
Python3
C#
PHP
Javascript
// C program to find second largest// element in an array #include <limits.h>#include <stdio.h> /* Function to print the second largest elements */void print2largest(int arr[], int arr_size){    int i, first, second;     /* There should be atleast two elements */    if (arr_size < 2) {        printf(" Invalid Input ");        return;    }     first = second = INT_MIN;    for (i = 0; i < arr_size; i++) {        /* If current element is greater than first           then update both first and second */        if (arr[i] > first) {            second = first;            first = arr[i];        }         /* If arr[i] is in between first and           second then update second  */        else if (arr[i] > second && arr[i] != first)            second = arr[i];    }    if (second == INT_MIN)        printf("There is no second largest element\n");    else        printf("The second largest element is %d", second);} /* Driver program to test above function */int main(){    int arr[] = { 12, 35, 1, 10, 34, 1 };    int n = sizeof(arr) / sizeof(arr[0]);    print2largest(arr, n);    return 0;}
// C++ program to find the second largest element #include <iostream>using namespace std; // returns the index of second largest// if second largest didn't exist return -1int secondLargest(int arr[], int n) {    int first = 0, second = -1;    for (int i = 1; i < n; i++) {        if (arr[i] > arr[first]) {            second = first;            first = i;        }        else if (arr[i] < arr[first]) {            if (second == -1 || arr[second] < arr[i])                second = i;        }    }    return second;} int main() {    int arr[] = {10, 12, 20, 4};    int index = secondLargest(arr, sizeof(arr)/sizeof(arr[0]));    if (index == -1)        cout << "Second Largest didn't exist";    else        cout << "Second largest : " << arr[index];}
// JAVA Code for Find Second largest// element in an arrayclass GFG {     /* Function to print the second largest    elements */    public static void print2largest(int arr[],                                     int arr_size)    {        int i, first, second;         /* There should be atleast two elements */        if (arr_size < 2) {            System.out.print(" Invalid Input ");            return;        }         first = second = Integer.MIN_VALUE;        for (i = 0; i < arr_size; i++) {            /* If current element is greater than            first then update both first and second */            if (arr[i] > first) {                second = first;                first = arr[i];            }             /* If arr[i] is in between first and               second then update second  */            else if (arr[i] > second && arr[i] != first)                second = arr[i];        }         if (second == Integer.MIN_VALUE)            System.out.print("There is no second largest"                             + " element\n");        else            System.out.print("The second largest element"                             + " is " + second);    }     /* Driver program to test above function */    public static void main(String[] args)    {        int arr[] = { 12, 35, 1, 10, 34, 1 };        int n = arr.length;        print2largest(arr, n);    }}// This code is contributed by Arnav Kr. Mandal.
# Python program to# find second largest# element in an array  # Function to print the# second largest elementsdef print2largest(arr, arr_size):     # There should be atleast        # two elements    if (arr_size < 2):             print(" Invalid Input ")        return          first = second = -2147483648    for i in range(arr_size):             # If current element is                # smaller than first        # then update both                # first and second        if (arr[i] > first):                     second = first            first = arr[i]                  # If arr[i] is in                # between first and        # second then update second        elif (arr[i] > second and arr[i] != first):            second = arr[i]         if (second == -2147483648):        print("There is no second largest element")    else:        print("The second largest element is", second)  # Driver program to test# above functionarr = [12, 35, 1, 10, 34, 1]n = len(arr) print2largest(arr, n) # This code is contributed# by Anant Agarwal.
// C# Code for Find Second largest// element in an arrayusing System; class GFG {     // Function to print the    // second largest elements    public static void print2largest(int[] arr,                                     int arr_size)    {        int i, first, second;         // There should be atleast two elements        if (arr_size < 2) {            Console.WriteLine(" Invalid Input ");            return;        }         first = second = int.MinValue;        for (i = 0; i < arr_size; i++) {            // If current element is smaller than            // first then update both first and second            if (arr[i] > first) {                second = first;                first = arr[i];            }             // If arr[i] is in between first            // and second then update second            else if (arr[i] > second && arr[i] != first)                second = arr[i];        }         if (second == int.MinValue)            Console.Write("There is no second largest"                          + " element\n");        else            Console.Write("The second largest element"                          + " is " + second);    }     // Driver Code    public static void Main(String[] args)    {        int[] arr = { 12, 35, 1, 10, 34, 1 };        int n = arr.Length;        print2largest(arr, n);    }} // This code is contributed by Parashar.
<?php// PHP program to find second largest// element in an array // Function to print the// second largest elementsfunction print2largest($arr, $arr_size){     // There should be atleast    // two elements    if ($arr_size < 2)    {        echo(" Invalid Input ");        return;    }     $first = $second = PHP_INT_MIN;    for ($i = 0; $i < $arr_size ; $i++)    {                 // If current element is        // smaller than first        // then update both        // first and second        if ($arr[$i] > $first)        {            $second = $first;            $first = $arr[$i];        }         // If arr[i] is in        // between first and        // second then update        // second        else if ($arr[$i] > $second &&                 $arr[$i] != $first)            $second = $arr[$i];    }    if ($second == PHP_INT_MIN)        echo("There is no second largest element\n");    else        echo("The second largest element is " . $second . "\n");} // Driver Code$arr = array(12, 35, 1, 10, 34, 1);$n = sizeof($arr);print2largest($arr, $n); // This code is contributed by Ajit.?>
<script>  // Javascript program to find second largest// element in an array       // Function to print the second largest elements    function print2largest(arr, arr_size) {        let i;        let largest = second = -2454635434;           // There should be atleast two elements        if (arr_size < 2) {            document.write(" Invalid Input ");            return;        }           // finding the largest element                 for (i = 0 ;i<arr_size;i++){            if (arr[i]>largest){                second = largest ;                largest = arr[i]            }             else if (arr[i]!=largest && arr[i]>second ){                second = arr[i];            }        }          if (second == -2454635434){                     document.write("There is no second largest element<br>");        }        else{            document.write("The second largest element is " + second);                return;            }        }          // Driver program to test above function      let arr= [ 12, 35, 1, 10, 34, 1 ];    let n = arr.length;    print2largest(arr, n);      // This code is contributed by Shaswat Singh  </script>
Output:
Second largest : 34
Complexity Analysis:
Time Complexity: O(n). Only one traversal of the array is needed.
Auxiliary space: O(1). As no extra space is required.
Related Article: Smallest and second smallest element in an arrayThis article is contributed by Harsh Agarwal. If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above. 
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