[LeetCode]Unique Paths II

 

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.

 

java code : 一维的动态规划，遇到障碍设为0即可。

 

 

public class Solution {  
    public int uniquePathsWithObstacles(int[][] obstacleGrid) {  
        // IMPORTANT: Please reset any member data you declared, as  
        // the same Solution instance will be reused for each test case.  
        int row = obstacleGrid.length;  
        if(row == 0)  
            return 0;  
        int col = obstacleGrid[0].length;  
        if(col == 0)  
            return 0;  
        if(obstacleGrid[0][0] == 1 || obstacleGrid[row-1][col-1] == 1)  
            return 0;  
        int[][] dp = new int[row][col];  
        dp[0][0] = 1;  
        for(int i = 1; i < col; i++)  
        {  
            if(obstacleGrid[0][i] == 1)  
                dp[0][i] = 0;  
            else dp[0][i] = dp[0][i-1];  
        }  
        for(int i = 1; i < row; i++)  
        {  
            if(obstacleGrid[i][0] == 1)  
                dp[i][0] = 0;  
            else dp[i][0] = dp[i-1][0];  
        }  
        for(int i = 1; i < row; i++)  
        {  
            for(int j = 1; j < col; j++)  
            {  
                if(obstacleGrid[i][j] == 1)  
                    dp[i][j] = 0;  
                else  
                {  
                    dp[i][j] = dp[i][j-1] + dp[i-1][j];  
                }  
            }  
        }  
        int res = dp[row-1][col-1];  
        for(int i = 0; i < row; i++)  
            dp[i] = null;  
        dp = null;  
        return res;  
    }  
}  

 

补充：软件开发 , C++ ,