LeetCode进阶之路（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.

题目：这道题是上一题的升级版，中间加了一个障碍，其实只要把障碍地方的解变为 0 就好。

public class Solution {    public int uniquePathsWithObstacles(int[][] obstacleGrid) {        int row = obstacleGrid.length;        if(row < 1 ) return 0;        int col = obstacleGrid[0].length;        if(col < 1) return 0;                if(obstacleGrid[0][0] == 1|| obstacleGrid[row-1][col-1]==1) return 0;                for(int i = 0;i < row;i++) {            for(int j = 0;j < col;j++) {                if(obstacleGrid[i][j] == 1){                    obstacleGrid[i][j] = -1;                }            }        }                for(int i = 0;i < row;i++){            if(obstacleGrid[i][0] == -1) {                break;            } else {                obstacleGrid[i][0] = 1;            }        }                for(int i = 0;i < col;i++){            if(obstacleGrid[0][i] == -1) {                break;            } else {                obstacleGrid[0][i] = 1;            }        }                for(int i = 1;i < row;i++) {            for(int j = 1;j < col;j++) {                if(obstacleGrid[i][j] != -1) {                    if(obstacleGrid[i-1][j] ==-1 && obstacleGrid[i][j-1] == -1) {                        continue;                    }else if(obstacleGrid[i-1][j] ==-1) {                        obstacleGrid[i][j] = obstacleGrid[i][j-1];                    } else if(obstacleGrid[i][j-1] == -1) {                        obstacleGrid[i][j] = obstacleGrid[i-1][j];                    } else {                        obstacleGrid[i][j] = obstacleGrid[i-1][j] + obstacleGrid[i][j-1];                    }                }            }        }        return obstacleGrid[row-1][col-1];    }

种一棵树最好的时间是十年前，其次是现在！

一忙就忘了更新这事，看来得定个闹钟提醒自己了！