[leetcode]Unique Paths II

动态规划。再最左和最上加了0的一行一列。但是一开始忘了把mx[1][1]设成1了。

public class Solution {
    public int uniquePathsWithObstacles(int[][] obstacleGrid) {
        // Start typing your Java solution below
        // DO NOT write main() function
        int m = obstacleGrid.length;
        if (m == 0) return 0;
        int n = obstacleGrid[0].length;
        if (n == 0) return 0;
        
        int[][] mx= new int[m+1][n+1];
        for (int i = 0; i <= m; i++) {
            mx[i][0] = 0;
        }      
        for (int j = 0; j <= n; j++) {
            mx[0][j] = 0;
        }
        
        for (int i = 1; i <= m; i++) {
            for (int j = 1; j <= n; j++) {
                if (obstacleGrid[i-1][j-1] == 1) {
                    mx[i][j] = 0;
                }
                else {
                    if (i == 1 && j == 1) mx[i][j] = 1;
                    else mx[i][j] = mx[i][j-1] + mx[i-1][j];
                }                
            }
        }
        
        return mx[m][n];
    }
}