1253. Reconstruct a 2-Row Binary Matrix

Given the following details of a matrix with n columns and 2 rows :

  • The matrix is a binary matrix, which means each element in the matrix can be 0 or 1.
  • The sum of elements of the 0-th(upper) row is given as upper.
  • The sum of elements of the 1-st(lower) row is given as lower.
  • The sum of elements in the i-th column(0-indexed) is colsum[i], where colsum is given as an integer array with length n.

Your task is to reconstruct the matrix with upper, lower and colsum.

Return it as a 2-D integer array.

If there are more than one valid solution, any of them will be accepted.

If no valid solution exists, return an empty 2-D array.

 

Example 1:

Input: upper = 2, lower = 1, colsum = [1,1,1]
Output: [[1,1,0],[0,0,1]]
Explanation: [[1,0,1],[0,1,0]], and [[0,1,1],[1,0,0]] are also correct answers.

Example 2:

Input: upper = 2, lower = 3, colsum = [2,2,1,1]
Output: []

Example 3:

Input: upper = 5, lower = 5, colsum = [2,1,2,0,1,0,1,2,0,1]
Output: [[1,1,1,0,1,0,0,1,0,0],[1,0,1,0,0,0,1,1,0,1]]

 

Constraints:

  • 1 <= colsum.length <= 10^5
  • 0 <= upper, lower <= colsum.length
  • 0 <= colsum[i] <= 2

Rust Solution

struct Solution;

impl Solution {
    fn reconstruct_matrix(mut upper: i32, mut lower: i32, colsum: Vec<i32>) -> Vec<Vec<i32>> {
        let n = colsum.len();
        let mut res = vec![vec![0; n]; 2];
        for j in 0..n {
            match colsum[j] {
                2 => {
                    res[0][j] = 1;
                    res[1][j] = 1;
                    upper -= 1;
                    lower -= 1;
                }
                1 => {
                    if upper >= lower {
                        res[0][j] = 1;
                        upper -= 1;
                    } else {
                        res[1][j] = 1;
                        lower -= 1;
                    }
                }
                _ => {}
            }
        }
        if upper == 0 && lower == 0 {
            res
        } else {
            vec![]
        }
    }
}

#[test]
fn test() {
    let upper = 2;
    let lower = 1;
    let colsum = vec![1, 1, 1];
    let res = vec_vec_i32![[1, 1, 0], [0, 0, 1]];
    assert_eq!(Solution::reconstruct_matrix(upper, lower, colsum), res);
    let upper = 2;
    let lower = 3;
    let colsum = vec![2, 2, 1, 1];
    let res = vec_vec_i32![];
    assert_eq!(Solution::reconstruct_matrix(upper, lower, colsum), res);
    let upper = 5;
    let lower = 5;
    let colsum = vec![2, 1, 2, 0, 1, 0, 1, 2, 0, 1];
    let res = vec_vec_i32![
        [1, 1, 1, 0, 0, 0, 1, 1, 0, 0],
        [1, 0, 1, 0, 1, 0, 0, 1, 0, 1]
    ];
    assert_eq!(Solution::reconstruct_matrix(upper, lower, colsum), res);
}

Having problems with this solution? Click here to submit an issue on github.