[LeetCode]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

.
动态规划，注意把受阻塞的置0.

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