LeetCode 62 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.

思路：与LeetCode 61 Unique Paths 的思路一样点/article/1333769.html

public class Solution {
	public int uniquePathsWithObstacles(int[][] obstacleGrid) {
		int m = obstacleGrid.length;
		int n = obstacleGrid[0].length;

		int[][] grid = new int[m]
;
		int i, j;
		boolean flag = false;

		for (i = 0; i < m; i++) {
			if (obstacleGrid[i][0] == 1)
				flag = true;
			if (!flag)
				grid[i][0] = 1;
		}

		flag = false;
		for (i = 0; i < n; i++) {
			if (obstacleGrid[0][i] == 1)
				flag = true;
			if (!flag)
				grid[0][i] = 1;
		}

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