. [Swift] LeetCode1253 reconstructed binary matrix row 2 | Reconstruct a 2-Row Binary Matrix

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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

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Give you a  2 line of  n binary array columns:

• Matrix is a binary matrix, which means that each element of the matrix is not  0 that  1.
• The first  0 element of the row and is  upper.
• The first  1 element of the row and is  lower.
• The first  i column (from the  0 elements of the numbered) and is  colsum[i], colsum is a length  n of an array of integers.

You need to use  upper, lower and  colsum to reconstruct this matrix, and return it in the form of a two-dimensional array of integers.

If there are several different answers, so any one can by this question.

If there is no satisfactory answer, please return to an empty two-dimensional 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]] is the correct answer.

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]]

prompt:

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