Algorithm
Problem Name: 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
0or1. - 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], wherecolsumis given as an integer array with lengthn.
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 <= 10^50 <= upper, lower <= colsum.length0 <= colsum[i] <= 2
Code Examples
#1 Code Example with Python Programming
Code -
Python Programming
class Solution:
def reconstructMatrix(
self, upper: int, lower: int, colsum: List[int]
) -> List[List[int]]:
res = [[0] * len(colsum) for _ in range(2)]
for j, sm in enumerate(colsum):
if sm == 2:
if upper == 0 or lower == 0:
return []
upper -= 1
lower -= 1
res[0][j] = res[1][j] = 1
elif sm:
if upper == lower == 0:
return []
if upper >= lower:
upper -= 1
res[0][j] = 1
else:
lower -= 1
res[1][j] = 1
return res if upper == lower == 0 else []
Input
upper = 2, lower = 1, colsum = [1,1,1]
Output
[[1,1,0],[0,0,1]]