1253-reconstruct-a-2-row-binary-matrix.adoc

1253. Reconstruct a 2-Row Binary Matrix

{leetcode}/problems/reconstruct-a-2-row-binary-matrix/[LeetCode - 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

思路分析

为什么需要现在 upper 和 lower 中先减去 2 的数量呢？没想明白

一刷

link:{sourcedir}/_1253_ReconstructA2RowBinaryMatrix.java[role=include]

参考资料

1. 1253. 重构 2 行二进制矩阵 - 官方题解