算法题day42（补5.28日卡：动态规划02）

今天的动态规划都是二维的，与昨日不同。

一、刷题：

1.leetcode题目 62. 不同路径 - 力扣（LeetCode）（medium,）

解决：

class Solution:def uniquePaths(self, m: int, n: int) -> int:dp = [[0]*n for _ in range(m)]##易错点 第一行和第一列要初始化for j in range(n):dp[0][j] = 1for i in range(m):dp[i][0] = 1for i in range(1,m):for j in range(1,n):dp[i][j] = dp[i-1][j] + dp[i][j-1]return dp[m-1][n-1]

2.leetcode题目 63. 不同路径 II - 力扣（LeetCode）

解决：

class Solution:def uniquePathsWithObstacles(self, obstacleGrid: List[List[int]]) -> int:m = len(obstacleGrid)n = len(obstacleGrid[0])if obstacleGrid[m-1][n-1] == 1 or obstacleGrid[0][0]==1:return 0dp = [[0]*n for _ in range(m)]for i in range(m):if obstacleGrid[i][0] == 0:dp[i][0] = 1else:breakfor j in range(n):if obstacleGrid[0][j] == 0:dp[0][j] = 1else:breakfor i in range(1,m):for j in range(1,n):if obstacleGrid[i][j] == 1:dp[i][j] = 0continuedp[i][j] = dp[i-1][j] + dp[i][j-1]return dp[m-1][n-1]