A cell of a grid is balanced when the sum of its row equals the sum of its column. Given a grid of
integers grid, return how many cells are balanced.
Examples
Input: grid = [[1, 2, 0],
[0, 1, 0]]
Output: 2
Explanation: row sums are 3 and 1; column sums are 1, 3 and 0.
Cell (0,1) has row sum 3 and column sum 3; cell (1,0) has row sum 1 and column sum 1.
Input: grid = [[2, 1],
[1, 2]]
Output: 4
Input: grid = [[5]]
Output: 1
Constraints
1 <= rows, cols <= 100,-1000 <= grid[r][c] <= 1000
Goals
- Precompute row and column sums before the main loop
- Count cells satisfying a condition on their row and column