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题目链接:https://leetcode.com/problems/unique-paths-ii/
题目:
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
.
Note: m and n will be at most 100.
思路:
动态规划。easy
算法:
public int uniquePathsWithObstacles(int[][] obstacleGrid) { int c[][] = new int[obstacleGrid.length][obstacleGrid[0].length]; c[0][0] = obstacleGrid[0][0] == 0 ? 1 : 0; for (int i = 1; i < obstacleGrid.length; i++) { c[i][0] = (c[i-1][0]!=0&&obstacleGrid[i][0] == 0) ? 1 : 0; } for (int j = 1; j < obstacleGrid[0].length; j++) { c[0][j] = (c[0][j-1]!=0&&obstacleGrid[0][j] == 0) ? 1 : 0; } for (int i = 1; i < obstacleGrid.length; i++) { for (int j = 1; j < obstacleGrid[0].length; j++) { if (obstacleGrid[i][j] != 1){ c[i][j] = c[i - 1][j] + c[i][j - 1]; } else c[i][j] = 0; } } return c[obstacleGrid.length - 1][obstacleGrid[0].length - 1]; }
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原文地址:http://blog.csdn.net/yeqiuzs/article/details/51501298