m*n的格子里面,机器人在左上角,每次行动向下或者想右一格,请问可能的方案

"""62. Unique PathsMedium113781FavoriteShareA 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?https://assets.leetcode.com/uploads/2018/10/22/robot_maze.pngAbove is a 7 x 3 grid. How many possible unique paths are there?Note: m and n will be at most 100.Example 1:Input: m = 3, n = 2Output: 3Explanation:From the top-left corner, there are a total of 3 ways to reach the bottom-right corner:1. Right -> Right -> Down2. Right -> Down -> Right3. Down -> Right -> RightExample 2:Input: m = 7, n = 3Output: 28"""

动规即可

class Solution:    def uniquePaths(self, m, n):        """        :type m: int        :type n: int        :rtype: int        """        mat = [[0 for i in range(n)]for j in range(m)]        mat[0][0] = 1        for j in range(1, n):            mat[0][j] = 1        for i in range(1, m):            mat[i][0] = 1        for i in range(1, m):            for j in range(1, n):                mat[i][j] = mat[i-1][j] + mat[i][j-1]        return mat[m-1][n-1]