Description
Given a grid of 0s and 1s, count the number of axis-aligned rectangles that can be formed using only grid cells marked with 1 as corners.
Examples
Input:
grid = [[1,0,0,1,0],[0,0,1,0,1],[0,0,0,1,0],[1,0,1,0,1]]Output:
1Explanation:
One corner rectangle.
Input:
grid = [[1]]Output:
1Explanation:
Minimal case with a single-element matrix.
Input:
grid = [[1,1,0],[1,1,0],[0,0,1]]Output:
1Explanation:
There is one corner rectangle formed by the 1s at positions (0,0), (0,1), (1,0), and (1,1). These four 1s form a 2x2 rectangle in the top-left corner of the grid.
Constraints
- •
1 ≤ rows, cols ≤ 200