A Boolean Matrix Question

Given a boolean matrix mat[M][N] of size M X N, modify it such that if a matrix cell mat[i][j] is 1 (or true) then make all the cells of ith row and jth column as 1. 

Examples:

Input: {{1, 0},
           {0, 0}}
Output: {{1, 1}
              {1, 0}}
Input: {{0, 0, 0},
            {0, 0, 1}}
Output: {{0, 0, 1},
               {1, 1, 1}}

Input: {{1, 0, 0, 1},
           {0, 0, 1, 0},
          {0, 0, 0, 0}}
Output: {{1, 1, 1, 1},
               {1, 1, 1, 1},
              {1, 0, 1, 1}}

Follow the steps below to solve the problem

• Create two temporary arrays row[M] and col[N]. Initialize all values of row[] and col[] as 0. 
• Traverse the input matrix mat[M][N]. If you see an entry mat[i][j] as true, then mark row[i] and col[j] as true. 
• Traverse the input matrix mat[M][N] again. For each entry mat[i][j], check the values of row[i] and col[j]. If any of the two values (row[i] or col[j]) is true, then mark mat[i][j] as true.

Below is the implementation of the above approach:

C++

// C++ Code For A Boolean Matrix Question
#include <bits/stdc++.h>

using namespace std;
#define R 3
#define C 4

void modifyMatrix(bool mat[R][C])
{
    bool row[R];
    bool col[C];

    int i, j;

    /* Initialize all values of row[] as 0 */
    for (i = 0; i < R; i++)
        row[i] = 0;

    /* Initialize all values of col[] as 0 */
    for (i = 0; i < C; i++)
        col[i] = 0;

    // Store the rows and columns to be marked as
    // 1 in row[] and col[] arrays respectively
    for (i = 0; i < R; i++) {
        for (j = 0; j < C; j++) {
            if (mat[i][j] == 1) {
                row[i] = 1;
                col[j] = 1;
            }
        }
    }

    // Modify the input matrix mat[] using the
    // above constructed row[] and col[] arrays
    for (i = 0; i < R; i++)
        for (j = 0; j < C; j++)
            if (row[i] == 1 || col[j] == 1)
                mat[i][j] = 1;
}

/* A utility function to print a 2D matrix */
void printMatrix(bool mat[R][C])
{
    int i, j;
    for (i = 0; i < R; i++) {
        for (j = 0; j < C; j++)
            cout << mat[i][j];
        cout << endl;
    }
}

// Driver Code
int main()
{
    bool mat[R][C] = { { 1, 0, 0, 1 },
                       { 0, 0, 1, 0 },
                       { 0, 0, 0, 0 } };

    cout << "Input Matrix \n";
    printMatrix(mat);
    modifyMatrix(mat);
    printf("Matrix after modification \n");
    printMatrix(mat);
    return 0;
}

// This code is contributed by Aditya Kumar (adityakumar129)

C

// C Code For A Boolean Matrix Question
#include <stdbool.h>
#include <stdio.h>

#define R 3
#define C 4

void modifyMatrix(bool mat[R][C])
{
    bool row[R];
    bool col[C];

    int i, j;

    /* Initialize all values of row[] as 0 */
    for (i = 0; i < R; i++)
        row[i] = 0;

    /* Initialize all values of col[] as 0 */
    for (i = 0; i < C; i++)
        col[i] = 0;

    // Store the rows and columns to be marked as
    // 1 in row[] and col[] arrays respectively
    for (i = 0; i < R; i++) {
        for (j = 0; j < C; j++) {
            if (mat[i][j] == 1) {
                row[i] = 1;
                col[j] = 1;
            }
        }
    }

    // Modify the input matrix mat[] using the
    // above constructed row[] and col[] arrays
    for (i = 0; i < R; i++)
        for (j = 0; j < C; j++)
            if (row[i] == 1 || col[j] == 1)
                mat[i][j] = 1;
}

/* A utility function to print a 2D matrix */
void printMatrix(bool mat[R][C])
{
    int i, j;
    for (i = 0; i < R; i++) {
        for (j = 0; j < C; j++)
            printf("%d ", mat[i][j]);
        printf("\n");
    }
}

// Driver Code
int main()
{
    bool mat[R][C] = { { 1, 0, 0, 1 },
                       { 0, 0, 1, 0 },
                       { 0, 0, 0, 0 } };

    printf("Input Matrix \n");
    printMatrix(mat);
    modifyMatrix(mat);
    printf("Matrix after modification \n");
    printMatrix(mat);
    return 0;
}

// This code is contributed by Aditya Kumar (adityakumar129)

Java

// Java Code For A Boolean Matrix Question
import java.io.*;

class GFG {
    public static void modifyMatrix(int mat[][], int R,
                                    int C)
    {
        int row[] = new int[R];
        int col[] = new int[C];
        int i, j;

        /* Initialize all values of row[] as 0 */
        for (i = 0; i < R; i++)
            row[i] = 0;

        /* Initialize all values of col[] as 0 */
        for (i = 0; i < C; i++)
            col[i] = 0;

        /* Store the rows and columns to be marked as
        1 in row[] and col[] arrays respectively */
        for (i = 0; i < R; i++) {
            for (j = 0; j < C; j++) {
                if (mat[i][j] == 1) {
                    row[i] = 1;
                    col[j] = 1;
                }
            }
        }

        /* Modify the input matrix mat[] using the
        above constructed row[] and col[] arrays */
        for (i = 0; i < R; i++)
            for (j = 0; j < C; j++)
                if (row[i] == 1 || col[j] == 1)
                    mat[i][j] = 1;
    }

    /* A utility function to print a 2D matrix */
    public static void printMatrix(int mat[][], int R,
                                   int C)
    {
        int i, j;
        for (i = 0; i < R; i++) {
            for (j = 0; j < C; j++)
                System.out.print(mat[i][j] + " ");
            System.out.println();
        }
    }

    /* Driver program to test above functions */
    public static void main(String[] args)
    {
        int mat[][] = {
            { 1, 0, 0, 1 },
            { 0, 0, 1, 0 },
            { 0, 0, 0, 0 },
        };

        System.out.println("Matrix Initially");
        printMatrix(mat, 3, 4);
        modifyMatrix(mat, 3, 4);
        System.out.println("Matrix after modification");
        printMatrix(mat, 3, 4);
    }
}

// This code is contributed by Aditya Kumar (adityakumar129)

Python3

# Python3 Code For A Boolean Matrix Question
R = 3
C = 4


def modifyMatrix(mat):
    row = [0] * R
    col = [0] * C

    # Initialize all values of row[] as 0
    for i in range(0, R):
        row[i] = 0

    # Initialize all values of col[] as 0
    for i in range(0, C):
        col[i] = 0

    # Store the rows and columns to be marked
    # as 1 in row[] and col[] arrays respectively
    for i in range(0, R):

        for j in range(0, C):
            if (mat[i][j] == 1):
                row[i] = 1
                col[j] = 1

    # Modify the input matrix mat[] using the
    # above constructed row[] and col[] arrays
    for i in range(0, R):

        for j in range(0, C):
            if (row[i] == 1 or col[j] == 1):
                mat[i][j] = 1

# A utility function to print a 2D matrix


def printMatrix(mat):
    for i in range(0, R):

        for j in range(0, C):
            print(mat[i][j], end=" ")
        print()


# Driver Code
mat = [[1, 0, 0, 1],
       [0, 0, 1, 0],
       [0, 0, 0, 0]]

print("Input Matrix")
printMatrix(mat)

modifyMatrix(mat)

print("Matrix after modification")
printMatrix(mat)

# This code is contributed by Nikita Tiwari.

C#

// C# Code For A Boolean
// Matrix Question
using System;

class GFG {
    public static void modifyMatrix(int[, ] mat, int R,
                                    int C)
    {
        int[] row = new int[R];
        int[] col = new int[C];
        int i, j;

        /* Initialize all values
        of row[] as 0 */
        for (i = 0; i < R; i++) {
            row[i] = 0;
        }

        /* Initialize all values
        of col[] as 0 */
        for (i = 0; i < C; i++) {
            col[i] = 0;
        }

        /* Store the rows and columns
        to be marked as 1 in row[]
        and col[] arrays respectively */
        for (i = 0; i < R; i++) {
            for (j = 0; j < C; j++) {
                if (mat[i, j] == 1) {
                    row[i] = 1;
                    col[j] = 1;
                }
            }
        }

        /* Modify the input matrix
        mat[] using the above
        constructed row[] and
        col[] arrays */
        for (i = 0; i < R; i++) {
            for (j = 0; j < C; j++) {
                if (row[i] == 1 || col[j] == 1) {
                    mat[i, j] = 1;
                }
            }
        }
    }

    /* A utility function to
    print a 2D matrix */
    public static void printMatrix(int[, ] mat, int R,
                                   int C)
    {
        int i, j;
        for (i = 0; i < R; i++) {
            for (j = 0; j < C; j++) {
                Console.Write(mat[i, j] + " ");
            }
            Console.WriteLine();
        }
    }

    // Driver code
    static public void Main()
    {
        int[, ] mat = { { 1, 0, 0, 1 },
                        { 0, 0, 1, 0 },
                        { 0, 0, 0, 0 } };

        Console.WriteLine("Matrix Initially");

        printMatrix(mat, 3, 4);

        modifyMatrix(mat, 3, 4);
        Console.WriteLine("Matrix after "
                          + "modification");
        printMatrix(mat, 3, 4);
    }
}

// This code is contributed by ajit

PHP

<?php
// PHP Code For A Boolean
// Matrix Question
$R = 3;
$C = 4;

function modifyMatrix(&$mat)
{
    global $R,$C;
    $row = array();
    $col = array();

    /* Initialize all values
       of row[] as 0 */
    for ($i = 0; $i < $R; $i++)
    {
        $row[$i] = 0;
    }


    /* Initialize all values
       of col[] as 0 */
    for ($i = 0; $i < $C; $i++)
    {
        $col[$i] = 0;
    }


    /* Store the rows and columns
       to be marked as 1 in row[]
       and col[] arrays respectively */
    for ($i = 0; $i < $R; $i++)
    {
        for ($j = 0; $j < $C; $j++)
        {
            if ($mat[$i][$j] == 1)
            {
                $row[$i] = 1;
                $col[$j] = 1;
            }
        }
    }

    /* Modify the input matrix mat[]
       using the above constructed
       row[] and col[] arrays */
    for ($i = 0; $i < $R; $i++)
    {
        for ($j = 0; $j < $C; $j++)
        {
            if ($row[$i] == 1 ||
                $col[$j] == 1 )
            {
                $mat[$i][$j] = 1;
            }
        }
    }
}

/* A utility function to
   print a 2D matrix */
function printMatrix(&$mat)
{
    global $R, $C;
    for ($i = 0; $i < $R; $i++)
    {
        for ($j = 0; $j < $C; $j++)
        {
            echo $mat[$i][$j] . " ";
        }
        echo "\n";
    }
}

// Driver code
$mat = array(array(1, 0, 0, 1),
             array(0, 0, 1, 0),
             array(0, 0, 0, 0));

echo "Input Matrix \n";
printMatrix($mat);

modifyMatrix($mat);

echo "Matrix after modification \n";
printMatrix($mat);

// This code is contributed
// by ChitraNayal
?>

Javascript

<script>

// Javascript Code For A Boolean Matrix Question

    function modifyMatrix(mat,R,C)
    {
        let row=new Array(R);
        let col = new Array(C);

        /* Initialize all values of row[] as 0 */
        for (i = 0; i < R; i++)
        {
            row[i] = 0;
        }

        /* Initialize all values of col[] as 0 */
        for (i = 0; i < C; i++)
        {
            col[i] = 0;

        }

        /* Store the rows and columns to be marked as
        1 in row[] and col[] arrays respectively */
        for (i = 0; i < R; i++)
        {
            for (j = 0; j < C; j++)
            {
                if (mat[i][j] == 1)
                {
                    row[i] = 1;
                    col[j] = 1;
                }
            }
        }

        /* Modify the input matrix mat[] using the
        above constructed row[] and col[] arrays */
        for (i = 0; i < R; i++)
        {
            for (j = 0; j < C; j++)
            {
                if ( row[i] == 1 || col[j] == 1 )
                {
                    mat[i][j] = 1;
                }
            }
        }
    }

    /* A utility function to print a 2D matrix */
    function printMatrix(mat,R,C)
    {
        let i, j;
        for (i = 0; i < R; i++)
        {
            for (j = 0; j < C; j++)
            {
                document.write(mat[i][j]+ " ");
            }
            document.write("<br>");
        }
    }

    /* Driver program to test above functions */

    let mat = [[1, 0, 0, 1],[0, 0, 1, 0],[0, 0, 0, 0]];
    document.write("Matrix Initially <br>")
    printMatrix(mat, 3, 4);
    modifyMatrix(mat, 3, 4);
    document.write("Matrix after modification n <br>");
    printMatrix(mat, 3, 4);

    // This code is contributed by avanitrachhadiya2155

</script>

Output

Input Matrix 
1001
0010
0000
Matrix after modification 
1111
1111
1011

Time Complexity: O(M*N), Traversing over the matrix two times.
Auxiliary Space: O(M + N), Taking two arrays one of size M and another of size N.

Thanks to Dixit Sethi for suggesting this method. 

A Boolean Matrix Question using O(1) Space:

This method is a space-optimized version of above method. This method uses the first row and first column of the input matrix in place of the auxiliary arrays row[] and col[] of above method. First take care of the first row and column and store the info about these two in two flag variables rowFlag and colFlag. Once we have this info, we can use the first row and first column as auxiliary arrays and apply method 1 for submatrix (matrix excluding first row and first column) of size (M-1)*(N-1).

Follow the steps to solve the problem:

• Scan the first row and set a variable rowFlag to indicate whether we need to set all 1s in the first row or not. 
• Scan the first column and set a variable colFlag to indicate whether we need to set all 1s in the first column or not. 
• Use the first row and first column as the auxiliary arrays row[] and col[] respectively, consider the matrix as a submatrix starting from the second row and second column, and apply above method.
• Finally, using rowFlag and colFlag, update the first row and first column if needed.

Below is the implementation of above approach:

C++

#include <bits/stdc++.h>
using namespace std;
#define R 3
#define C 4

void modifyMatrix(int mat[R][C])
{
    // variables to check if there are any 1
    // in first row and column
    bool row_flag = false;
    bool col_flag = false;

    // updating the first row and col if 1
    // is encountered
    for (int i = 0; i < R; i++) {
        for (int j = 0; j < C; j++) {
            if (i == 0 && mat[i][j] == 1)
                row_flag = true;

            if (j == 0 && mat[i][j] == 1)
                col_flag = true;

            if (mat[i][j] == 1) {

                mat[0][j] = 1;
                mat[i][0] = 1;
            }
        }
    }

    // Modify the input matrix mat[] using the
    // first row and first column of Matrix mat
    for (int i = 1; i < R; i++)
        for (int j = 1; j < C; j++)
            if (mat[0][j] == 1 || mat[i][0] == 1)
                mat[i][j] = 1;

    // modify first row if there was any 1
    if (row_flag == true)
        for (int i = 0; i < C; i++)
            mat[0][i] = 1;

    // modify first col if there was any 1
    if (col_flag == true)
        for (int i = 0; i < R; i++)
            mat[i][0] = 1;
}

/* A utility function to print a 2D matrix */
void printMatrix(int mat[R][C])
{
    for (int i = 0; i < R; i++) {
        for (int j = 0; j < C; j++)
            cout << mat[i][j] << " ";
        cout << "\n";
    }
}

// Driver function to test the above function
int main()
{

    int mat[R][C] = { { 1, 0, 0, 1 },
                      { 0, 0, 1, 0 },
                      { 0, 0, 0, 0 } };

    cout << "Input Matrix :\n";
    printMatrix(mat);
    modifyMatrix(mat);
    cout << "Matrix After Modification :\n";
    printMatrix(mat);
    return 0;
}

// This code is contributed by Aditya Kumar (adityakumar129)

C

#include <stdbool.h>
#include <stdio.h>

#define R 3
#define C 4

void modifyMatrix(int mat[R][C])
{
    // variables to check if there are any 1
    // in first row and column
    bool row_flag = false;
    bool col_flag = false;

    // updating the first row and col if 1
    // is encountered
    for (int i = 0; i < R; i++) {
        for (int j = 0; j < C; j++) {
            if (i == 0 && mat[i][j] == 1)
                row_flag = true;

            if (j == 0 && mat[i][j] == 1)
                col_flag = true;

            if (mat[i][j] == 1) {
                mat[0][j] = 1;
                mat[i][0] = 1;
            }
        }
    }

    // Modify the input matrix mat[] using the
    // first row and first column of Matrix mat
    for (int i = 1; i < R; i++)
        for (int j = 1; j < C; j++)
            if (mat[0][j] == 1 || mat[i][0] == 1)
                mat[i][j] = 1;

    // modify first row if there was any 1
    if (row_flag == true)
        for (int i = 0; i < C; i++)
            mat[0][i] = 1;

    // modify first col if there was any 1
    if (col_flag == true)
        for (int i = 0; i < R; i++)
            mat[i][0] = 1;
}

/* A utility function to print a 2D matrix */
void printMatrix(int mat[R][C])
{
    for (int i = 0; i < R; i++) {
        for (int j = 0; j < C; j++)
            printf("%d ", mat[i][j]);
        printf("\n");
    }
}

// Driver function to test the above function
int main()
{

    int mat[R][C] = { { 1, 0, 0, 1 },
                      { 0, 0, 1, 0 },
                      { 0, 0, 0, 0 } };

    printf("Input Matrix :\n");
    printMatrix(mat);
    modifyMatrix(mat);
    printf("Matrix After Modification :\n");
    printMatrix(mat);
    return 0;
}

// This code is contributed by Aditya Kumar (adityakumar129)

Java

import java.io.*;
class GFG {
    public static void modifyMatrix(int mat[][])
    {
        // variables to check if there are any 1
        // in first row and column
        boolean row_flag = false;
        boolean col_flag = false;

        // updating the first row and col if 1
        // is encountered
        for (int i = 0; i < mat.length; i++) {
            for (int j = 0; j < mat[0].length; j++) {
                if (i == 0 && mat[i][j] == 1)
                    row_flag = true;

                if (j == 0 && mat[i][j] == 1)
                    col_flag = true;

                if (mat[i][j] == 1) {

                    mat[0][j] = 1;
                    mat[i][0] = 1;
                }
            }
        }

        // Modify the input matrix mat[] using the
        // first row and first column of Matrix mat
        for (int i = 1; i < mat.length; i++)
            for (int j = 1; j < mat[0].length; j++)
                if (mat[0][j] == 1 || mat[i][0] == 1)
                    mat[i][j] = 1;

        // modify first row if there was any 1
        if (row_flag == true)
            for (int i = 0; i < mat[0].length; i++)
                mat[0][i] = 1;

        // modify first col if there was any 1
        if (col_flag == true)
            for (int i = 0; i < mat.length; i++)
                mat[i][0] = 1;
    }

    /* A utility function to print a 2D matrix */
    public static void printMatrix(int mat[][])
    {
        for (int i = 0; i < mat.length; i++) {
            for (int j = 0; j < mat[0].length; j++)
                System.out.print(mat[i][j] + " ");
            System.out.println("");
        }
    }

    // Driver function to test the above function
    public static void main(String args[])
    {
        int mat[][] = { { 1, 0, 0, 1 },
                        { 0, 0, 1, 0 },
                        { 0, 0, 0, 0 } };

        System.out.println("Input Matrix :");
        printMatrix(mat);
        modifyMatrix(mat);
        System.out.println("Matrix After Modification :");
        printMatrix(mat);
    }
}

// This code is contributed by Aditya Kumar (adityakumar129)

Python3

# Python3 Code For A Boolean Matrix Question
def modifyMatrix(mat):

    # variables to check if there are any 1
    # in first row and column
    row_flag = False
    col_flag = False

    # updating the first row and col
    # if 1 is encountered
    for i in range(0, len(mat)):

        for j in range(0, len(mat)):
            if (i == 0 and mat[i][j] == 1):
                row_flag = True

            if (j == 0 and mat[i][j] == 1):
                col_flag = True

            if (mat[i][j] == 1):
                mat[0][j] = 1
                mat[i][0] = 1

    # Modify the input matrix mat[] using the
    # first row and first column of Matrix mat
    for i in range(1, len(mat)):

        for j in range(1, len(mat) + 1):
            if (mat[0][j] == 1 or mat[i][0] == 1):
                mat[i][j] = 1

    # modify first row if there was any 1
    if (row_flag == True):
        for i in range(0, len(mat)):
            mat[0][i] = 1

    # modify first col if there was any 1
    if (col_flag == True):
        for i in range(0, len(mat)):
            mat[i][0] = 1

# A utility function to print a 2D matrix


def printMatrix(mat):

    for i in range(0, len(mat)):
        for j in range(0, len(mat) + 1):
            print(mat[i][j], end="")

        print()


# Driver Code
mat = [[1, 0, 0, 1],
       [0, 0, 1, 0],
       [0, 0, 0, 0]]

print("Input Matrix :")
printMatrix(mat)

modifyMatrix(mat)

print("Matrix After Modification :")
printMatrix(mat)

# This code is contributed by Nikita tiwari.

C#

// C# Code For A Boolean
// Matrix Question
using System;

class GFG {
    public static void modifyMatrix(int[, ] mat)
    {

        // variables to check
        // if there are any 1
        // in first row and column
        bool row_flag = false;
        bool col_flag = false;

        // updating the first
        // row and col if 1
        // is encountered
        for (int i = 0; i < mat.GetLength(0); i++) {
            for (int j = 0; j < mat.GetLength(1); j++) {
                if (i == 0 && mat[i, j] == 1)
                    row_flag = true;

                if (j == 0 && mat[i, j] == 1)
                    col_flag = true;

                if (mat[i, j] == 1) {
                    mat[0, j] = 1;
                    mat[i, 0] = 1;
                }
            }
        }

        // Modify the input matrix mat[]
        // using the first row and first
        // column of Matrix mat
        for (int i = 1; i < mat.GetLength(0); i++) {
            for (int j = 1; j < mat.GetLength(1); j++) {

                if (mat[0, j] == 1 || mat[i, 0] == 1) {
                    mat[i, j] = 1;
                }
            }
        }

        // modify first row
        // if there was any 1
        if (row_flag == true) {
            for (int i = 0; i < mat.GetLength(1); i++) {
                mat[0, i] = 1;
            }
        }

        // modify first col if
        // there was any 1
        if (col_flag == true) {
            for (int i = 0; i < mat.GetLength(0); i++) {
                mat[i, 0] = 1;
            }
        }
    }

    /* A utility function
    to print a 2D matrix */
    public static void printMatrix(int[, ] mat)
    {
        for (int i = 0; i < mat.GetLength(0); i++) {
            for (int j = 0; j < mat.GetLength(1); j++) {
                Console.Write(mat[i, j] + " ");
            }
            Console.Write("\n");
        }
    }

    // Driver Code
    public static void Main()
    {
        int[, ] mat = { { 1, 0, 0, 1 },
                        { 0, 0, 1, 0 },
                        { 0, 0, 0, 0 } };

        Console.Write("Input Matrix :\n");
        printMatrix(mat);

        modifyMatrix(mat);

        Console.Write("Matrix After "
                      + "Modification :\n");
        printMatrix(mat);
    }
}

// This code is contributed
// by ChitraNayal

PHP

<?php
// PHP Code For A Boolean
// Matrix Question
$R = 3;
$C = 4;

function modifyMatrix(&$mat)
{
    global $R, $C;

    // variables to check if
    // there are any 1 in
    // first row and column
    $row_flag = false;
    $col_flag = false;

    // updating the first
    // row and col if 1
    // is encountered
    for ($i = 0; $i < $R; $i++)
    {
        for ($j = 0; $j < $C; $j++)
        {
            if ($i == 0 && $mat[$i][$j] == 1)
                $row_flag = true;

            if ($j == 0 && $mat[$i][$j] == 1)
                $col_flag = true;

            if ($mat[$i][$j] == 1)
            {
                $mat[0][$j] = 1;
                $mat[$i][0] = 1;
            }
        }
    }

    // Modify the input matrix
    // mat[] using the first
    // row and first column of
    // Matrix mat
    for ($i = 1; $i < $R; $i++)
    {
        for ($j = 1; $j < $C; $j++)
        {
            if ($mat[0][$j] == 1 ||
                $mat[$i][0] == 1)
            {
                $mat[$i][$j] = 1;
            }
        }
    }

    // modify first row
    // if there was any 1
    if ($row_flag == true)
    {
        for ($i = 0; $i < $C; $i++)
        {
            $mat[0][$i] = 1;
        }
    }

    // modify first col
    // if there was any 1
    if ($col_flag == true)
    {
        for ($i = 0; $i < $R; $i++)
        {
            $mat[$i][0] = 1;
        }
    }
}

/* A utility function
to print a 2D matrix */
function printMatrix(&$mat)
{
    global $R, $C;
    for ($i = 0; $i < $R; $i++)
    {
        for ($j = 0; $j < $C; $j++)
        {
            echo $mat[$i][$j]." ";
        }
        echo "\n";
    }
}

// Driver Code
$mat = array(array(1, 0, 0, 1 ),
             array(0, 0, 1, 0 ),
             array(0, 0, 0, 0 ));

echo "Input Matrix :\n";
printMatrix($mat);

modifyMatrix($mat);

echo "Matrix After Modification :\n";
printMatrix($mat);

// This code is contributed
// by ChitraNayal
?>

Javascript

<script>

function modifyMatrix(mat)
{
    // variables to check if there are any 1
        // in first row and column
        let row_flag = false;
        let col_flag = false;

        // updating the first row and col if 1
        // is encountered
        for (let i = 0; i < mat.length; i++ ){
                for (let j = 0; j < mat[0].length; j++){
                        if (i == 0 && mat[i][j] == 1)
                            row_flag = true;

                        if (j == 0 && mat[i][j] == 1)
                            col_flag = true;

                        if (mat[i][j] == 1){

                            mat[0][j] = 1;
                            mat[i][0] = 1;
                        }

                    }
                }

        // Modify the input matrix mat[] using the
        // first row and first column of Matrix mat
        for (let i = 1; i < mat.length; i ++){
                for (let j = 1; j < mat[0].length; j ++){

                    if (mat[0][j] == 1 || mat[i][0] == 1){
                            mat[i][j] = 1;
                        }
                    }
                }

        // modify first row if there was any 1
        if (row_flag == true){
            for (let i = 0; i < mat[0].length; i++){
                        mat[0][i] = 1;
                    }
                }

        // modify first col if there was any 1
        if (col_flag == true){
            for (let i = 0; i < mat.length; i ++){
                        mat[i][0] = 1;
            }
        }
}

/* A utility function to print a 2D matrix */
function printMatrix(mat)
{
    for (let i = 0; i < mat.length; i ++){
            for (let j = 0; j < mat[0].length; j ++){
                document.write( mat[i][j] );
            }
                document.write("<br>");
        }
}

// Driver function to test the above function
let mat=[[1, 0, 0, 1],
                [0, 0, 1, 0],
                [0, 0, 0, 0]];
document.write("Input Matrix :<br>");
printMatrix(mat);

modifyMatrix(mat);

document.write("Matrix After Modification :<br>");
printMatrix(mat);

// This code is contributed by ab2127

</script>

Output

Input Matrix :
1 0 0 1 
0 0 1 0 
0 0 0 0 
Matrix After Modification :
1 1 1 1 
1 1 1 1 
1 0 1 1 

Time Complexity: O(M*N), Traversing over the matrix two times.
Auxiliary Space: O(1)

 Thanks to Sidh for suggesting this method.