leetcode-63 Unique Paths II
2016-11-04 17:51
495 查看
问题描述
地址:https://leetcode.com/problems/unique-paths-ii/描述:
Follow up for “Unique Paths”:
Now consider if some obstacles are added to the grids. How many unique paths would there be?
An obstacle and empty space is marked as 1 and 0 respectively in the grid.
For example,
There is one obstacle in the middle of a 3x3 grid as illustrated below.
[
[0,0,0],
[0,1,0],
[0,0,0]
]
The total number of unique paths is 2.
翻译:
在“Unique Paths”这个题目之后,现在考虑如果在格子中有障碍物,会有多少种方式使得机器人从左上角到右下角呢?
比方说给出一个3x3的格子:
[
[0,0,0],
[0,1,0],
[0,0,0]
]
最终返回从左上角到右下角的方式是2
问题解析
这个题目是与 http://blog.csdn.net/xiaoxiaoxuanao/article/details/53036116紧密相关的一个动态规划题目,在Unique Paths这个题目中我们已经得到过递推公式:
这个题目中我们只需要将障碍物(m,n)对应的A(m,n)设置为0即可,表示该位置不可通过。
例子中给出的矩阵对应的结果矩阵见下图:
解析代码
public int uniquePathsWithObstacles(int[][] obstacleGrid) { int m = obstacleGrid.length; int n = obstacleGrid[0].length; int[][] dp = new int[m] ; if(obstacleGrid[0][0] == 1){ return 0; } for(int i=0; i< m; i++){ for(int j =0; j<n; j++){ if(obstacleGrid[i][j] == 0){ if(i ==0 && j==0){ dp[i][j] =1; }else{ dp[i][j] = (i>0?dp[i-1][j]:0) + (j>0?dp[i][j-1]:0); } } } } return dp[m-1][n-1]; }
相关文章推荐
- LeetCode 63 - Unique Paths II
- leetcode_63题——Unique Paths II(动态规划)
- leetcode63-Unique Paths II
- Leetcode[63]-Unique Paths II
- LeetCode_OJ【63】Unique Paths II
- Leetcode 63 Unique Paths II
- Leetcode 63:Unique Paths II
- leetcode[63]Unique Paths II
- [LeetCode 63] Unique Paths II
- LeetCode 63 — Unique Paths II(C++ Java Python)
- Leetcode:63. Unique Paths II
- 算法分析与设计——LeetCode:63. Unique Paths II
- LeetCode_63---Unique Paths II
- (java)leetcode-63:Unique Paths II
- leetcode || 63、Unique Paths II
- 【leetcode】【63】Unique Paths II
- [leetcode 63] Unique Paths II
- LeetCode题库解答与分析——#63.不同路径IIUniquePathsII
- LeetCode -- 63 Unique Paths II
- [Leetcode 63, Medium] Unique Paths II