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

.

Note: m and n will be at most 100.

Dynamic programming.

public class Solution {
public int uniquePathsWithObstacles(int[][] obstacleGrid) {
if (obstacleGrid == null || obstacleGrid.length == 0 || obstacleGrid[0].length == 0) {
return 0;
}

int m = obstacleGrid.length;
int n = obstacleGrid[0].length;
int[][] path = new int[m]
;
for (int i = 0; i < n; i++) {
if (obstacleGrid[0][i] == 0) {
path[0][i] = 1;
} else {
for (int j = i; j < n; j++) {
path[0][j] = 0;
}
break;
}
}

for (int i = 0; i < m; i++) {
if (obstacleGrid[i][0] == 0) {
path[i][0] = 1;
} else {
for (int j = i; j < m; j++) {
path[j][0] = 0;
}
break;
}
}

for (int i = 1; i < m; i++) {
for (int j = 1; j < n; j++) {
if (obstacleGrid[i][j] == 1) {
path[i][j] = 0;
} else {
path[i][j] = path[i - 1][j] + path[i][j - 1];
}
}
}

return path[m - 1][n - 1];
}
}