【leetcode】62. Unique Paths

题目如下：

 

解题思路：没啥好说的，用动态规划，很容易得到递推表达式： dp[m] [n]= dp[m-1][n] + dp[m][n-1]。

代码如下：

class Solution(object):
    def uniquePaths(self, m, n):
        """
        :type m: int
        :type n: int
        :rtype: int
        """
        dp = [[0 for x in range(m)] for x in range(n)]
        dp[0][0] = 1
        for i in range(n):
            for j in range(m):
                if i-1 >=0:
                    dp[i][j] += dp[i-1][j]
                if j-1 >=0:
                    dp[i][j] += dp[i][j-1]
        #print dp
        return dp[n-1][m-1]