LeetCode 63. Unique Paths II

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.

和上一题一样的思路，每次需要判断一下当前位置是否可走就可以了。

class Solution {
public:
    int uniquePathsWithObstacles(vector<vector<int>>& obstacleGrid) {
        vector<vector<int>> dp(obstacleGrid.size()+1, vector<int>(obstacleGrid[0].size()+1, 0));
        if(obstacleGrid[0][0] == 0)
        	dp[1][1] = 1;
        for(int i=1; i<obstacleGrid.size()+1; ++ i)
        {
        	for(int j=1; j<obstacleGrid[0].size()+1; ++ j)
        	{
        		if(i == 1 && j == 1)
        			continue;
        		if(obstacleGrid[i-1][j-1] == 0)
        		{
        			dp[i][j] = dp[i-1][j] + dp[i][j-1];
        		}
        	}
        }
        return dp[obstacleGrid.size()][obstacleGrid[0].size()];
    }
};