Question

How to change all elements of row i and column j in a binary matrix to 0 if cell[i, j] is 0 in Rust

Answer 1

fn change_row_column(matrix: &mut Vec<Vec<i32>>, row: usize, col: usize) {
    let rows = matrix.len();
    let cols = matrix[0].len();

    for j in 0..cols {
        if matrix[row][j] != 0 {
            matrix[row][j] = -1;
        }
    }
    for i in 0..rows {
        if matrix[i][col] != 0 {
            matrix[i][col] = -1;
        }
    }
}

fn change_binary_matrix(matrix: &mut Vec<Vec<i32>>) {
    let rows = matrix.len();
    if rows == 0 {
        return;
    }
    let cols = matrix[0].len();
    if cols == 0 {
        return;
    }

    // First pass to mark affected rows and columns
    let mut positions = Vec::new();

    for i in 0..rows {
        for j in 0..cols {
            if matrix[i][j] == 0 {
                positions.push((i, j));
            }
        }
    }

    // Mark rows and columns
    for (i, j) in positions {
        change_row_column(matrix, i, j);
    }

    // Second pass to replace -1 with 0
    for i in 0..rows {
        for j in 0..cols {
            if matrix[i][j] == -1 {
                matrix[i][j] = 0;
            }
        }
    }
}

fn print_matrix(matrix: &Vec<Vec<i32>>) {
    for row in matrix {
        for val in row {
            print!("{} ", val);
        }
        println!();
    }
}

fn main() {
    let mut matrix = vec![
        vec![1, 1, 0, 1, 1, 1],
        vec![1, 1, 1, 1, 1, 1],
        vec![1, 1, 0, 1, 1, 1],
        vec![1, 1, 1, 1, 1, 1],
        vec![1, 0, 1, 1, 1, 1],
    ];

    change_binary_matrix(&mut matrix);
    print_matrix(&matrix);
}

 
 
/*
run:
   
0 0 0 0 0 0 
1 0 0 1 1 1 
0 0 0 0 0 0 
1 0 0 1 1 1 
0 0 0 0 0 0 

*/
 

 

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