https://leetcode.cn/problems/unique-paths/

递归
class Solution:
def uniquePaths(self, m: int, n: int) -> int:
if m == 1 or n == 1:
return 1
return self.uniquePaths(m, n - 1) + self.uniquePaths(m - 1, n)
动态
class Solution:
def uniquePaths(self, m: int, n: int) -> int:
dp = [[0] * n for _ in range(m)]
for i in range(n):
dp[0][i] = 1
for i in range(m):
dp[i][0] = 1
for i in range(1, m):
for j in range(1, n):
dp[i][j] = dp[i][j - 1] + dp[i - 1][j]
return dp[m - 1][n - 1]