Pair with given sum in matrix

Given a NxM matrix and a sum S. The task is to check if a pair with given Sum exists in the matrix or not.

Examples:

Input: mat[N][M] = {{1, 2, 3, 4},
                {5, 6, 7, 8},
                {9, 10, 11, 12},
                {13, 14, 15, 16}};
       sum = 31
Output: YES

Input: mat[N][M] = {{1, 2, 3, 4},
                {5, 6, 7, 8}};
       sum = 150
Output: NO

Approach:



  • Take a hash to store all elements of the matrix in the hash.
  • Start traversing through the matrix, and while traversing check if abs(sum-matrix_element) is present in the hash.
  • If present, then return true, else insert the current matrix element into the hash.
  • If all elements of the matrix are traversed and no pair is found, return false.

Below is the implementation of the above approach:

C++

filter_none

edit
close

play_arrow

link
brightness_4
code

// CPP code to check for pair with given sum
#include <bits/stdc++.h>
using namespace std;
  
#define N 4
#define M 4
  
// Function to check if a pair with given sum
// exists in the matrix
bool isPairWithSum(int mat[N][M], int sum)
{
    // hash to store elements
    unordered_set<int> s;
  
    // looping through elements
    // if present in the matrix
    // return true, else push
    // the element in matrix
    for (int i = 0; i < N; i++) {
        for (int j = 0; j < M; j++) {
            if (s.find(sum - mat[i][j]) != s.end()) {
                return true;
            }
            else {
                s.insert(mat[i][j]);
            }
        }
    }
  
    return false;
}
  
// Driver code
int main()
{
  
    // Input matrix
    int mat[N][M] = { { 1, 2, 3, 4 },
                      { 5, 6, 7, 8 },
                      { 9, 10, 11, 12 },
                      { 13, 14, 15, 16 } };
  
    // given sum
    int sum = 11;
  
    if (isPairWithSum(mat, sum)) {
        cout << "YES" << endl;
    }
    else
        cout << "NO" << endl;
  
    return 0;
}

chevron_right


Java

filter_none

edit
close

play_arrow

link
brightness_4
code

// Java code to check for pair
// with given sum
import java.util.*;
  
class GFG
{
      
// Function to check if a pair with 
// given sum exists in the matrix
static final int N = 4;
static final int M = 4;
static boolean isPairWithSum(int [][]mat, 
                             int sum)
{
    // hash to store elements
    Set<Integer> s = new HashSet<Integer>();
  
    // looping through elements
    // if present in the matrix
    // return true, else push
    // the element in matrix
    for (int i = 0; i < N; i++) 
    {
        for (int j = 0; j < M; j++)
        {
            if (s.contains(sum - mat[i][j])) 
            {
                return true;
            }
            else 
            {
                s.add(mat[i][j]);
            }
        }
    }
  
    return false;
}
  
// Driver code
public static void main(String []args)
{
  
    // Input matrix
    int [][]mat = { { 1, 2, 3, 4 },
                    { 5, 6, 7, 8 },
                    { 9, 10, 11, 12 },
                    { 13, 14, 15, 16 } };
  
    // given sum
    int sum = 11;
  
    if (isPairWithSum(mat, sum)) 
    {
        System.out.println("YES");
    }
    else
        System.out.println("NO");
}
}
  
// This code is contributed by ihritik 

chevron_right


C#

filter_none

edit
close

play_arrow

link
brightness_4
code

// C# code to check for pair
// with given sum
using System;
using System.Collections.Generic;
  
class GFG
{
      
// Function to check if a pair with 
// given sum exists in the matrix
static readonly int N = 4;
static readonly int M = 4;
static bool isPairWithSum(int [,]mat, 
                            int sum)
{
    // hash to store elements
    HashSet<int> s = new HashSet<int>();
  
    // looping through elements
    // if present in the matrix
    // return true, else push
    // the element in matrix
    for (int i = 0; i < N; i++) 
    {
        for (int j = 0; j < M; j++)
        {
            if (s.Contains(sum - mat[i, j])) 
            {
                return true;
            }
            else
            {
                s.Add(mat[i, j]);
            }
        }
    }
    return false;
}
  
// Driver code
public static void Main(String []args)
{
  
    // Input matrix
    int [,]mat = { { 1, 2, 3, 4 },
                    { 5, 6, 7, 8 },
                    { 9, 10, 11, 12 },
                    { 13, 14, 15, 16 } };
  
    // given sum
    int sum = 11;
  
    if (isPairWithSum(mat, sum)) 
    {
        Console.WriteLine("YES");
    }
    else
        Console.WriteLine("NO");
}
}
  
// This code contributed by Rajput-Ji

chevron_right


PHP

filter_none

edit
close

play_arrow

link
brightness_4
code

<?php 
// PHP code to check for pair with given sum
   
$N = 4;
$M = 4;
   
// Function to check if a pair with given sum
// exists in the matrix
function isPairWithSum(&$mat, $sum)
{
    global $N,$M;
    // array to store elements
    $s = array();
   
    // looping through elements
    // if present in the matrix
    // return true, else push
    // the element in matrix
    for ($i = 0; $i < $N; $i++) {
        for ($j = 0; $j < $M; $j++) {
            if (in_array($sum - $mat[$i][$j],$s) != end($s)) {
                return true;
            }
            else {
                array_push($s,$mat[$i][$j]);
            }
        }
    }
   
    return false;
}
   
// Driver code
  
    // Input matrix
    $mat = array(array( 1, 2, 3, 4 ),
                 array( 5, 6, 7, 8 ),
                 array( 9, 10, 11, 12 ),
                 array(13, 14, 15, 16 ));
   
    // given sum
    $sum = 11;
   
    if (isPairWithSum($mat, $sum)) {
        echo "YES" ."\n";
    }
    else
        echo "NO" ."\n";
   
    return 0;
?>

chevron_right


Output:

YES

Time Complexity: O(N*M)



My Personal Notes arrow_drop_up

Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.



Improved By : ihritik, chitranayal, Rajput-Ji



Article Tags :
Practice Tags :


Be the First to upvote.


Please write to us at contribute@geeksforgeeks.org to report any issue with the above content.