題目鏈接

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?

題目示例

解題思路

TODO （稍后補(bǔ)充）

解題代碼

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