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 7 x 3 grid. How many possible unique paths are there?
Note: m and n will be at most 100.
Example 1:
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 -> Right -> Down
2. Right -> Down -> Right
3. Down -> Right -> Right
Example 2:
Input: m = 7, n = 3
Output: 28
题解：
class Solution {
public:
int uniquePaths(int m, int n) {
vector<vector<int>> dp(n, vector<int>(m, 1));
for (int i = 1; i < n; i++) {
for (int j = 1; j < m; j++) {
dp[i][j] = dp[i - 1][j] + dp[i][j - 1];
}
}
return dp[n - 1][m - 1];
}
};