62. 不同路径

class Solution:
    def uniquePaths(self, m: int, n: int) -> int:
        dp=[[1 for _ in range(n)]  for _ in range(m)] 
        for i in range (1,m):
            for j in range(1,n):
                dp[i][j]= dp[i-1][j]+dp[i][j-1]
        return dp[-1][-1]