LeetCode-in-Java

1605. Find Valid Matrix Given Row and Column Sums

Medium

You are given two arrays rowSum and colSum of non-negative integers where rowSum[i] is the sum of the elements in the ith row and colSum[j] is the sum of the elements of the jth column of a 2D matrix. In other words, you do not know the elements of the matrix, but you do know the sums of each row and column.

Find any matrix of non-negative integers of size rowSum.length x colSum.length that satisfies the rowSum and colSum requirements.

Return a 2D array representing any matrix that fulfills the requirements. It’s guaranteed that at least one matrix that fulfills the requirements exists.

Example 1:

Input: rowSum = [3,8], colSum = [4,7]

Output: [[3,0], [1,7]]

Explanation:

0^th row: 3 + 0 = 3 == rowSum[0]

1^st row: 1 + 7 = 8 == rowSum[1]

0^th column: 3 + 1 = 4 == colSum[0]

1^st column: 0 + 7 = 7 == colSum[1]

The row and column sums match, and all matrix elements are non-negative.

Another possible matrix is: [[1,2], [3,5]]

Example 2:

Input: rowSum = [5,7,10], colSum = [8,6,8]

Output: [[0,5,0], [6,1,0], [2,0,8]]

Constraints:

• 1 <= rowSum.length, colSum.length <= 500
• 0 <= rowSum[i], colSum[i] <= 108
• sum(rows) == sum(columns)

Solution

public class Solution {
    public int[][] restoreMatrix(int[] rowSum, int[] colSum) {
        int[][] ans = new int[rowSum.length][colSum.length];
        for (int i = 0; i < rowSum.length; i++) {
            for (int j = 0; j < colSum.length; j++) {
                if (rowSum[i] != 0 && colSum[j] != 0) {
                    ans[i][j] = Math.min(rowSum[i], colSum[j]);
                    rowSum[i] -= ans[i][j];
                    colSum[j] -= ans[i][j];
                }
            }
        }
        return ans;
    }
}

This site is open source. Improve this page.