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.

原题链接：https://oj.leetcode.com/problems/unique-paths-ii/

此题与上一题的区别仅在于矩阵中有障碍的坐标点。

public class UniquePathsII {
	public int uniquePathsWithObstacles(int[][] obstacleGrid) {
		int m = obstacleGrid.length, n = obstacleGrid[0].length;
		int[][] dp = new int[m][n];
		for (int i = 0; i < m; i++) {
			for (int j = 0; j < n; j++) {
				if (obstacleGrid[i][j] == 0) {
					if (i == 0 && j == 0)
						dp[i][j] = 1;
					else if (i == 0)
						dp[i][j] = dp[i][j - 1];
					else if (j == 0)
						dp[i][j] = dp[i - 1][j];
					else
						dp[i][j] = dp[i - 1][j] + dp[i][j - 1];
				}
			}
		}
		return dp[m - 1][n - 1];
	}
}

LeetCode——Unique Paths II