leetcode——62.不同路径

class Solution:
    
    def uniquePaths(self, m: int, n: int) -> int:
        memo=[[0 for i in range(n)] for i in range(m)]#定义空二维数组
        for i in range(n):
            memo[0][i]=1
        for j in range(m):
            memo[j][0]=1
        for i in range(1,m):
            for j in range(1,n):
                memo[i][j]=memo[i-1][j]+memo[i][j-1]
        return memo[m-1][n-1]