Tutorialspoint.dev

Sorting rows of matrix in ascending order followed by columns in descending order

Given a matrix, sort the rows of matrix in ascending order followed by sorting the columns in descending order.
Examples :

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

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



1) Traverse all rows one by one and sort rows in ascending order using simple array sort.
2) Convert matrix to its transpose
3) Again sort all rows, but this time in ascending order.
4) Again convert matrix to its transpose

C++

// C++ implementation to sort the rows
// of matrix in ascending order followed by
// sorting the columns in descending order
#include <bits/stdc++.h>
using namespace std;
  
#define MAX_SIZE 10
  
// function to sort each row of the matrix
// according to the order specified by 
// ascending.
void sortByRow(int mat[][MAX_SIZE], int n, 
                           bool ascending)
{
    for (int i = 0; i < n; i++)
    {
      if (ascending)    
        sort(mat[i], mat[i] + n);
      else
          sort(mat[i], mat[i] + n, greater<int>());
    }      
}
  
// function to find transpose of the matrix
void transpose(int mat[][MAX_SIZE], int n)
{
    for (int i = 0; i < n; i++)
        for (int j = i + 1; j < n; j++) 
  
            // swapping element at index (i, j) 
            // by element at index (j, i)
            swap(mat[i][j], mat[j][i]);
}
  
// function to sort the matrix row-wise
// and column-wise
void sortMatRowAndColWise(int mat[][MAX_SIZE],
                                       int n)
{
    // sort rows of mat[][]
    sortByRow(mat, n, true);
  
    // get transpose of mat[][]
    transpose(mat, n);
  
    // again sort rows of mat[][] in descending
    // order.
    sortByRow(mat, n, false);
  
    // again get transpose of mat[][]
    transpose(mat, n);
}
  
// function to print the matrix
void printMat(int mat[][MAX_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 n = 3;
      
    int mat[n][MAX_SIZE]  = {{3, 2, 1},
                            {9, 8, 7}, 
                            {6, 5, 4}};
  
    cout << "Original Matrix: ";
    printMat(mat, n);
  
    sortMatRowAndColWise(mat, n);
  
    cout << " Matrix After Sorting: ";
    printMat(mat, n);
  
    return 0;
}

Java

// Java implementation to sort the rows
// of matrix in ascending order followed by
// sorting the columns in descending order
import java.util.Arrays;
import java.util.Collections;
  
class GFG
{
    static int MAX_SIZE=10;
      
    // function to sort each row of the matrix
    // according to the order specified by 
    // ascending.
    static void sortByRow(Integer mat[][], int n, 
                                 boolean ascending)
    {
        for (int i = 0; i < n; i++)
        {
            if (ascending) 
                Arrays.sort(mat[i]);
            else
                Arrays.sort(mat[i],Collections.reverseOrder());
        }     
    }
      
    // function to find transpose of the matrix
    static void transpose(Integer mat[][], int n)
    {
        for (int i = 0; i < n; i++)
            for (int j = i + 1; j < n; j++) 
            {
                // swapping element at index (i, j) 
                // by element at index (j, i)
                int temp = mat[i][j];
                mat[i][j] = mat[j][i];
                mat[j][i] = temp;
            }
    }
      
    // function to sort the matrix row-wise
    // and column-wise
    static void sortMatRowAndColWise(Integer mat[][],
                                              int n)
    {
        // sort rows of mat[][]
        sortByRow(mat, n, true);
      
        // get transpose of mat[][]
        transpose(mat, n);
      
        // again sort rows of mat[][] in descending
        // order.
        sortByRow(mat, n, false);
      
        // again get transpose of mat[][]
        transpose(mat, n);
    }
      
    // function to print the matrix
    static void printMat(Integer mat[][], int n)
    {
        for (int i = 0; i < n; i++) 
        {
            for (int j = 0; j < n; j++)
                System.out.print(mat[i][j] + " ");
            System.out.println();
        }
    }
      
    // Driver code
    public static void main (String[] args) 
    {
        int n = 3;
          
        Integer mat[][] = {{3, 2, 1},
                           {9, 8, 7}, 
                           {6, 5, 4}};
      
        System.out.print("Original Matrix: ");
        printMat(mat, n);
      
        sortMatRowAndColWise(mat, n);
      
        System.out.print(" Matrix After Sorting: ");
        printMat(mat, n);
    }
}
  
// This code is contributed by Anant Agarwal.

Python3

# Python implementation to sort the rows
# of matrix in ascending order followed by
# sorting the columns in descending order
  
MAX_SIZE=10
   
# function to sort each row of the matrix
# according to the order specified by 
# ascending.
def sortByRow(mat, n, ascending):
  
    for i in range(n):
        if (ascending):    
            mat[i].sort()
        else:
            mat[i].sort(reverse=True)
   
# function to find 
# transpose of the matrix
def transpose(mat, n):
  
    for i in range(n):
        for j in range(i + 1, n): 
          
            # swapping element at index (i, j) 
            # by element at index (j, i)
            temp = mat[i][j]
            mat[i][j] = mat[j][i]
            mat[j][i] = temp
  
# function to sort 
# the matrix row-wise
# and column-wise
def sortMatRowAndColWise(mat, n):
  
    # sort rows of mat[][]
    sortByRow(mat, n, True)
   
    # get transpose of mat[][]
    transpose(mat, n)
   
    # again sort rows of 
    # mat[][] in descending
    # order.
    sortByRow(mat, n, False)
   
    # again get transpose of mat[][]
    transpose(mat, n)
   
# function to print the matrix
def printMat(mat, n):
  
    for i in range(n):
        for j in range(n):
            print(mat[i][j] , " ", end="")
        print()
  
#Driver code
n = 3
       
mat = [[3, 2, 1],
    [9, 8, 7], 
    [6, 5, 4]]
   
print("Original Matrix:")
printMat(mat, n)
   
sortMatRowAndColWise(mat, n)
   
print("Matrix After Sorting:")
printMat(mat, n)
  
# This code is contributed
# by Anant Agarwal.

PHP


Output :

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

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


This article is attributed to GeeksforGeeks.org

leave a comment

code

0 Comments

load comments

Subscribe to Our Newsletter