【LeetCode】Unique Paths

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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.

递归超时，采用动态规划。

对于格点(i,j)。由于只能从上格点(i-1,j)或左格点(i,j-1)到达，并且两者路径是不重复的

因此count[i][j] = count[i-1][j]+count[i][j-1]

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

【LeetCode】Unique Paths

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原文地址：http://www.cnblogs.com/ganganloveu/p/4155220.html