0062. Unique Paths

https://leetcode.com/problems/unique-paths

Description

A robot is located at the top-left corner of a m x n grid (marked 'Start' in the diagram below).

The robot can only move either down or right at any point in time. The robot is trying to reach the bottom-right corner of the grid (marked 'Finish' in the diagram below).

How many possible unique paths are there?

Example 1:

**Input:** m = 3, n = 7
**Output:** 28

Example 2:

**Input:** m = 3, n = 2
**Output:** 3
**Explanation:**
From the top-left corner, there are a total of 3 ways to reach the bottom-right corner:
1. Right -> Down -> Down
2. Down -> Down -> Right
3. Down -> Right -> Down

Example 3:

**Input:** m = 7, n = 3
**Output:** 28

Example 4:

**Input:** m = 3, n = 3
**Output:** 6

Constraints:

• 1 <= m, n <= 100

• It's guaranteed that the answer will be less than or equal to 2 * 109.

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