Traverse a given Matrix using Recursion

Difficulty Level : Easy
Last Updated : 31 May, 2021

Given a matrix arr of size N x M, the task is to traverse this matrix using recursion.
Examples:

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

Input: M[][] = {{11, 12, 13}, 
                  {14, 15, 16}, 
                  {17, 18, 19}}
Output: 11, 12, 13, 14, 15, 16, 17, 18, 19

Approach: Below are the steps to traverse the Matrix recursively:

Base Case: If the current row or column exceeds the size N or M, respectively, the recursion is stopped.
- If the current column exceeds the total number of columns M, then the next row is started.

if (current_col >= M)
    This row ends.
    Start for next row

If the current row exceeds the total number of rows N, then the complete traversal is stopped.

if (current_row >= N)
    Matrix has been
    traversed completely

Recursive Case: In each recursive call,
1. The current element of the Matrix is printed.
2. Two recursive calls are made:
  - One to traverse the next row, and
  - Another to traverse the next column.

Below is the implementation of the above approach:

C++

// C++ program to traverse the matrix recursively
 
#include <iostream>
using namespace std;
 
#define N 2
#define M 3
 
// Function to traverse the matrix recursively
int traverseMatrix(int arr[N][M], int current_row,
                   int current_col)
{
    // If the entire column is traversed
    if (current_col >= M)
        return 0;
 
    // If the entire row is traversed
    if (current_row >= N)
        return 1;
 
    // Print the value of the current
    // cell of the matrix
    cout << arr[current_row][current_col] << ", ";
 
    // Recursive call to traverse the matrix
    // in the Horizontal direction
    if (traverseMatrix(arr, current_row,
                       current_col + 1)
        == 1)
        return 1;
 
    // Recursive call for changing the
    // Row of the matrix
    return traverseMatrix(arr,
                          current_row + 1,
                          0);
}
 
// Driver code
int main()
{
    int arr[N][M] = { { 1, 2, 3 },
                      { 4, 5, 6 } };
 
    traverseMatrix(arr, 0, 0);
    return 0;
}

Java

// Java program to traverse the matrix recursively
class GFG {
     
    final static int N = 2;
    final static int  M = 3;
     
    // Function to traverse the matrix recursively
    static int traverseMatrix(int arr[][], int current_row,
                       int current_col)
    {
        // If the entire column is traversed
        if (current_col >= M)
            return 0;
     
        // If the entire row is traversed
        if (current_row >= N)
            return 1;
     
        // Print the value of the current
        // cell of the matrix
        System.out.print(arr[current_row][current_col] + ", ");
     
        // Recursive call to traverse the matrix
        // in the Horizontal direction
        if (traverseMatrix(arr, current_row,
                           current_col + 1)
            == 1)
            return 1;
     
        // Recursive call for changing the
        // Row of the matrix
        return traverseMatrix(arr,
                              current_row + 1,
                              0);
    }
     
    // Driver code
    public static void main (String[] args)
    {
        int arr[][] = { { 1, 2, 3 },
                          { 4, 5, 6 } };
     
        traverseMatrix(arr, 0, 0);
    }
}
 
// This code is contributed by AnkitRai01

C#

// C# program to traverse the matrix recursively
 
using System;
 
public class GFG {
     
    static int N = 2;
    static int  M = 3;
     
    // Function to traverse the matrix recursively
    static int traverseMatrix(int [,]arr, int current_row,
                       int current_col)
    {
        // If the entire column is traversed
        if (current_col >= M)
            return 0;
     
        // If the entire row is traversed
        if (current_row >= N)
            return 1;
     
        // Print the value of the current
        // cell of the matrix
        Console.Write(arr[current_row,current_col] + ", ");
     
        // Recursive call to traverse the matrix
        // in the Horizontal direction
        if (traverseMatrix(arr, current_row,
                           current_col + 1)
            == 1)
            return 1;
     
        // Recursive call for changing the
        // Row of the matrix
        return traverseMatrix(arr,
                              current_row + 1,
                              0);
    }
     
    // Driver code
    public static void Main (string[] args)
    {
        int [,]arr = { { 1, 2, 3 },
                          { 4, 5, 6 } };
     
        traverseMatrix(arr, 0, 0);
    }
}
 
// This code is contributed by AnkitRai01

Python3

# Python3 program to traverse the matrix recursively
N = 2
M = 3
 
# Function to traverse the matrix recursively
def traverseMatrix(arr, current_row, current_col) :
 
    # If the entire column is traversed
    if (current_col >= M) :
        return 0;
 
    # If the entire row is traversed
    if (current_row >= N) :
        return 1;
 
    # Print the value of the current
    # cell of the matrix
    print(arr[current_row][current_col],end= ", ");
 
    # Recursive call to traverse the matrix
    # in the Horizontal direction
    if (traverseMatrix(arr, current_row, current_col + 1 ) == 1) :
        return 1;
         
    # Recursive call for changing the
    # Row of the matrix
    return traverseMatrix(arr, current_row + 1, 0);
 
# Driver code
if __name__ == "__main__" :
    arr = [ [ 1, 2, 3 ],
            [ 4, 5, 6 ] ];
 
    traverseMatrix(arr, 0, 0);
 
# This code is contributed by AnkitRai01

Javascript

<script>
// Javascript program to traverse the matrix recursively
 
let N = 2
let M = 3
 
// Function to traverse the matrix recursively
function traverseMatrix(arr, current_row, current_col)
{
    // If the entire column is traversed
    if (current_col >= M)
        return 0;
 
    // If the entire row is traversed
    if (current_row >= N)
        return 1;
 
    // Print the value of the current
    // cell of the matrix
    document.write(arr[current_row][current_col] + ", ");
 
    // Recursive call to traverse the matrix
    // in the Horizontal direction
    if (traverseMatrix(arr, current_row,
                    current_col + 1)
        == 1)
        return 1;
 
    // Recursive call for changing the
    // Row of the matrix
    return traverseMatrix(arr,
                        current_row + 1,
                        0);
}
 
// Driver code
 
let arr = [ [ 1, 2, 3 ],
            [ 4, 5, 6 ] ];
 
traverseMatrix(arr, 0, 0);
</script>

Output:

1, 2, 3, 4, 5, 6,

Time Complexity: O(N * M)

Auxiliary Space: O(M), because of recursive calling

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