leetcode JAVA Unique Paths II 难度系数3 3.21

Question：

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.

public class Solution {
public int uniquePathsWithObstacles(int[][] obstacleGrid) {
int row = obstacleGrid.length;
int column = obstacleGrid[0].length;
int[][] dp = new int[row][column];
if (obstacleGrid[0][0] == 1) {
dp[0][0] = 0;
} else {
dp[0][0] = 1;
}
for (int i = 1; i < row; i++) {
if (obstacleGrid[i][0] == 1) {
dp[i][0] = 0;
} else {
dp[i][0] = dp[i - 1][0];
}
}
for (int j = 1; j < column; j++) {
if (obstacleGrid[0][j] == 1) {
dp[0][j] = 0;
} else {
dp[0][j] = dp[0][j-1];
}
}
for (int i = 1; i < row; i++) {
for (int j = 1; j < column; j++) {
if (obstacleGrid[i][j] == 1) {
dp[i][j] = 0;
} else {
dp[i][j] = dp[i - 1][j]+dp[i][j - 1];
}
}
}
return dp[row - 1][column - 1];
}
}