[LeetCode]63 Unique Paths II

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

http://blog.csdn.net/linhuanmars/article/details/22135231

public class Solution {
    public int uniquePathsWithObstacles(int[][] obstacleGrid) {
        
        // Validations
        if (obstacleGrid == null || obstacleGrid.length == 0 || obstacleGrid[0].length == 0)
            return 0;   // Invalid input
        
        int m = obstacleGrid.length;
        int n = obstacleGrid[0].length;
        
        int[][] paths = new int[m][n];
        for (int i = 0 ; i < m ; i ++)
        {
            for (int j = 0 ; j < n ; j ++)
            {
                int v = 0;
                if (obstacleGrid[i][j] == 1)
                {
                    // obstacle
                    v = 0;
                }
                else if (i == 0 && j == 0)
                {
                    // Start point
                    v = 1;
                }
                else
                {
                    int left = j > 0 ? paths[i][j - 1] : 0;
                    int up = i > 0 ? paths[i - 1][j] : 0;
                    v = left + up;
                }
                paths[i][j] = v;
            }
        }
        return paths[m - 1][n - 1];
    }
}