Unique Paths
Part of Practice: Grids & Two Strings
A robot sits in the top-left corner of an m x n grid and wants to reach the bottom-right corner. On every move it can only go one cell right or one cell down — never left or up.
Count how many distinct paths exist from the top-left cell to the bottom-right cell.
Constraints: 1 <= m, n <= 100, and the answer is guaranteed to fit in a 32-bit integer.
Examples
- Input:
- m = 3, n = 7
- Output:
- 28
- Input:
- m = 3, n = 2
- Output:
- 3
Three paths: (right, down, down), (down, down, right), (down, right, down).
- Input:
- m = 2, n = 2
- Output:
- 2
Either right-then-down or down-then-right.
Hints
One at a time — struggle first, peek second.
Your thinking space — verify on LeetCode, then mark it.