Java for LeetCode 063 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.

解题思路：

本题如果使用上题中的解法一，将会非常复杂，因此我们修改解法二即可，JAVA实现如下：

public int uniquePathsWithObstacles(int[][] obstacleGrid) {
        int[] v = new int[obstacleGrid[0].length];
		for (int i = 0; i < v.length; i++)
			if (obstacleGrid[0][i] == 0)
				v[i] = 1;
			else
				break;
		for (int i = 1; i < obstacleGrid.length; i++) {
			if (obstacleGrid[i][0] == 1)
				v[0] = 0;
			for (int j = 1; j < v.length; j++)
				if (obstacleGrid[i][j] == 1)
					v[j] = 0;
				else
					v[j] += v[j - 1];
		}
		return v[v.length - 1];
    }