2023.12.14 Today's Challenge

https://leetcode.com/problems/special-positions-in-a-binary-matrix/

Special Positions in a Binary Matrix - LeetCode

압축해서 count 하는 식으로 판단하면 됨

class Solution:
    def numSpecial(self, mat: List[List[int]]) -> int:
        m, n = len(mat), len(mat[0])
        r_cnt, c_cnt = [0]*m, [0]*n

        for r in range(m):
            for c in range(n):
                if mat[r][c] == 1:
                    r_cnt[r] += 1
                    c_cnt[c] += 1
        
        ans = 0

        for r in range(m):
            for c in range(n):
                if mat[r][c] == 1:
                    if r_cnt[r] == 1 and c_cnt[c] == 1:
                        ans += 1
        
        return ans