# Question

Formatted question description: https://leetcode.ca/all/62.html

```
62 Unique Paths
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?
Above is a 3 x 7 grid. How many possible unique paths are there?
Note: m and n will be at most 100.
@tag-array
```

# Algorithm

Using Dynamic Programming to solve, you can maintain a two-dimensional array dp, where `dp[i][j]`

represents the number of different moves to the current position, and then the state transition equation can be obtained as: `dp[i][j ] = dp[i-1][j] + dp[i][j-1]`

, here in order to save space, use a one-dimensional array dp, refresh line by line.

# Code

Java