Question Definition
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.
My Java Solution
public int uniquePathsWithObstacles(int[][] obstacleGrid) {
if(obstacleGrid.length == 0 || obstacleGrid[0].length == 0 || obstacleGrid[0][0] == 1)
return 0;
int[][] dp = new int[obstacleGrid.length + 1][obstacleGrid[0].length + 1];
for(int i = 1; i < dp.length; i++){
for(int j = 1; j < dp[i].length; j++){
if(i == 1 && j == 1)
dp[i][j] = 1;
else if(obstacleGrid[i - 1][j - 1] == 1)
dp[i][j] = 0;
else{
dp[i][j] = dp[i - 1][j] + dp[i][j - 1];
}
}
}
return dp[obstacleGrid.length][obstacleGrid[0].length];
}
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