LeetCode||62. 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?
挺经典的动态规划，当前数字为矩阵上一格和左一格的和
class Solution(object):
def uniquePaths(self, m, n):
"""
:type m: int
:type n: int
:rtype: int
"""
f = [([1] * n) for i in range(m)]
for i in range(1, m):
for j in range(1, n):
f[i][j] = f[i-1][j] + f[i][j-1]
return f[-1][-1]