【Leetcode】Unique Paths II

题目链接：https://leetcode.com/problems/unique-paths-ii/

题目：

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.

思路：

动态规划。easy

算法：

public int uniquePathsWithObstacles(int[][] obstacleGrid) {
int c[][] = new int[obstacleGrid.length][obstacleGrid[0].length];
c[0][0] = obstacleGrid[0][0] == 0 ? 1 : 0;
for (int i = 1; i < obstacleGrid.length; i++) {
c[i][0] = (c[i-1][0]!=0&&obstacleGrid[i][0] == 0) ? 1 : 0;
}
for (int j = 1; j < obstacleGrid[0].length; j++) {
c[0][j] = (c[0][j-1]!=0&&obstacleGrid[0][j] == 0) ? 1 : 0;
}

for (int i = 1; i < obstacleGrid.length; i++) {
for (int j = 1; j < obstacleGrid[0].length; j++) {
if (obstacleGrid[i][j] != 1){
c[i][j] = c[i - 1][j] + c[i][j - 1];
}
else
c[i][j] = 0;
}
}
return c[obstacleGrid.length - 1][obstacleGrid[0].length - 1];
}