63. Unique Paths II

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.

Solution

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

        int[][] result = new int[m][n];

        for(int i = 0; i < m; i ++) {
            if (obstacleGrid[i][0] == 0) {
                result[i][0] = 1;
            } else {
                break;
            }
        }

        for(int j = 0; j < n; j ++) {
            if (obstacleGrid[0][j] == 0) {
                result[0][j] = 1;
            } else {
                break;
            }
        }

        for(int i = 1; i < m; i ++) {
            for(int j = 1; j < n; j ++) {
                if (obstacleGrid[i][j] == 0) {
                    result[i][j] = result[i - 1][j] + result[i][j - 1];

                }
            }
        }

        return result[m-1][n-1];
    }
}