LeetCode—62. Unique Paths

Type：medium

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?

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给定一幅格子，从左上角格子走起，只能向下或向右走，问走到右下角格子有几种方法？

dp题。设原点为(0， 0)，则dp[i][j] = dp[i-1][j] + dp[i][j-1]。

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class Solution {

public:

    int uniquePaths(int m, int n) {

        vector> dp(m, vector(n, 0));

        for(int i=0; i

        for(int i=1; i

        for(int i=1; i

            for(int j=1; j

                dp[i][j] = dp[i-1][j] + dp[i][j-1];

            }

        }

        return dp[m-1][n-1];

    }

};