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