Boolean Matrix

Boolean Matrix

Problem Statement

Given a boolean matrix of size RxC where each cell contains either 0 or 1, modify it such that if a matrix cell matrix[i][j] is 1 then all the cells in its ith row and jth column will become 1.

Example 1

Input :
R = 2, C = 2
matrix[][] = {{1, 0},
              {0, 0}}

Output : 
1 1
1 0

Explanation : Only cell that has 1 is at (0,0) so all cells in row 0 are modified to 1 and all cells in column 0 are modified to 1.

Example 2

Input :
R = 4, C = 3
matrix[][] = {{ 1, 0, 0},
              { 1, 0, 0},
              { 1, 0, 0},
              { 0, 0, 0}}

Output :
1 1 1
1 1 1
1 1 1
1 0 0

Explanation : The position of cells that have 1 in the original matrix are (0,0), (1,0) and (2,0). Therefore, all cells in row 0,1,2 are and column 0 are modified to 1. 

Task

You dont need to read input or print anything. Complete the function booleanMatrix() that takes the matrix as input parameter and modifies it in-place.

Expected Time Complexity : O(R * C).
Expected Auxiliary Space : O(R + C)

Constraints :
1 <= R, C <= 100
1 <= mat[i][j] <= 1

Solutions

Java Solution

class Solution
{
    //Function to modify the matrix such that if a matrix cell matrix[i][j]
    //is 1 then all the cells in its ith row and jth column will become 1.
    void booleanMatrix(int matrix[][])
    {
        // code here
        int row = matrix.length;
        int col = matrix[0].length;
        int matRow[] = new int[row];
        int matCol[] = new int[col];
        for(int i=0; i<row; i++) {
            matRow[i] = 0;
        }
            
        for(int j=0; j<col; j++) {
            matCol[j] = 0;
        }
            
        for(int i=0; i<row; i++) {
            for(int j=0; j<col; j++) {
                if(matrix[i][j] == 1) {
                    matRow[i] = 1;
                    matCol[j] = 1;
                    }
            }
        }
            
        for(int i=0; i<row; i++) {
            for(int j=0; j<col; j++) {
                if(matRow[i] == 1 || matCol[j] == 1) {
                    matrix[i][j] = 1;
                    }
            }
        }
    }
}