C++ Program to Sort the given matrix

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Given a n x n matrix. The problem is to sort the given matrix in strict order. Here strict order means that matrix is sorted in a way such that all elements in a row are sorted in increasing order and for row ‘i’, where 1 <= i <= n-1, first element of row ‘i’ is greater than or equal to the last element of row ‘i-1’.
Examples:

Input : mat[][] = { {5, 4, 7},
                    {1, 3, 8},
                    {2, 9, 6} }
Output : 1 2 3
         4 5 6
         7 8 9

Approach: Create a temp[] array of size n^2. Starting with the first row one by one copy the elements of the given matrix into temp[]. Sort temp[]. Now one by one copy the elements of temp[] back to the given matrix.

C++

// C++ implementation to sort the given matrix 
#include <bits/stdc++.h> 
using namespace std; 
  
#define SIZE 10 
  
// function to sort the given matrix 
void sortMat(int mat[SIZE][SIZE], int n) 
{ 
    // temporary matrix of size n^2 
    int temp[n * n]; 
    int k = 0; 
  
    // copy the elements of matrix one by one 
    // into temp[] 
    for (int i = 0; i < n; i++) 
        for (int j = 0; j < n; j++) 
            temp[k++] = mat[i][j]; 
  
    // sort temp[] 
    sort(temp, temp + k); 
      
    // copy the elements of temp[] one by one 
    // in mat[][] 
    k = 0; 
    for (int i = 0; i < n; i++) 
        for (int j = 0; j < n; j++) 
            mat[i][j] = temp[k++]; 
} 
  
// function to print the given matrix 
void printMat(int mat[SIZE][SIZE], int n) 
{ 
    for (int i = 0; i < n; i++) { 
        for (int j = 0; j < n; j++) 
            cout << mat[i][j] << " "; 
        cout << endl; 
    } 
} 
  
// Driver program to test above 
int main() 
{ 
    int mat[SIZE][SIZE] = { { 5, 4, 7 }, 
                            { 1, 3, 8 }, 
                            { 2, 9, 6 } }; 
    int n = 3; 
  
    cout << "Original Matrix: 
"; 
    printMat(mat, n); 
  
    sortMat(mat, n); 
  
    cout << " 
Matrix After Sorting: 
"; 
    printMat(mat, n); 
  
    return 0; 
} 

Output:

Original Matrix:
5 4 7
1 3 8
2 9 6

Matrix After Sorting:
1 2 3
4 5 6
7 8 9

Time Complexity: O(n²log₂n).
Auxiliary Space: O(n²).

Please refer complete article on Sort the given matrix for more details!

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