63. Unique Paths II (Graph; DP)
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
.
class Solution { public: int uniquePathsWithObstacles(vector<vector<int> > &obstacleGrid) { int m = obstacleGrid.size(); int n = obstacleGrid[0].size(); int dp[m][n]; if(obstacleGrid[0][0] == 1) return 0; dp[0][0] = 1; for(int i = 1; i< n; i++ ) { if(obstacleGrid[0][i] == 1) dp[0][i] = 0; else dp[0][i] = dp[0][i-1]; } for(int i = 1; i< m; i++ ) { if(obstacleGrid[i][0] == 1) dp[i][0] = 0; else dp[i][0] = dp[i-1][0]; } for(int i = 1; i< m; i++) { for(int j = 1; j< n; j++) { if(obstacleGrid[i][j] == 1) dp[i][j] = 0; else dp[i][j] = dp[i-1][j] + dp[i][j-1]; } } return dp[m-1][n-1]; } };