LeetCode in Kotlin

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

class Solution {
    fun restoreMatrix(rowSum: IntArray, colSum: IntArray): Array<IntArray> {
        val ans = Array(rowSum.size) { IntArray(colSum.size) }
        for (i in rowSum.indices) {
            for (j in colSum.indices) {
                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
    }
}

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