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.

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class Solution {public:    int uniquePaths(int m, int n) {        if(m==0||n==0) return 0;        vector< vector<int>> dp(m,vector<int>(n,1));        for(int i=1;i<m;++i)        for(int j=1;j<n;++j)        {            dp[i][j]=dp[i][j-1]+dp[i-1][j];        }        return dp[m-1][n-1];    }};