#include <vector>
class Solution {
public:
    int uniquePaths(int m, int n) {
        vector<vector<int>> dp(m,vector<int>(n));
        for(int i = 0; i < m; i++){
            dp[i][0] = 1;
        }//初始第一一列

        for(int j = 0; j < n; j++){
            dp[0][j] = 1;
        }//初始化第一行
        for(int i = 1; i < m; i++){
            for(int j = 1; j < n; j++ )
            dp[i][j] = dp[i-1][j] + dp[i][j-1];//
        }
        return dp[m-1][n-1];
        
    }
};