Leetcode: UniquePath II

Description:

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.

分析：这道题目跟之前的UniquePath基本都是一样的，只是在格子中加了障碍物。基本思路是深搜+备忘录

但是不知道为什么会超时。。基本就跟答案一样，以后分析

int pathrec[102][102]={0};
class Solution {
public:

    int findpath(vector<vector<int> >& grid, int m, int n,int x,int y)
    {
        if(grid[m][n]==1)
            return 0;
        
        if(pathrec[m][n]!=0)
            return pathrec[m][n];
        int pathnum = 0;
        if(m==x-1 && n==y-1)
        {
            pathrec[m][n] = 1;
            return 1;
        }
        
        if(m+1<x) pathnum+= findpath(grid,m+1,n,x,y);
        if(n+1<y) pathnum+= findpath(grid,m,n+1,x,y);
        pathrec[m][n] = pathnum;
        return pathnum;
    }
    int uniquePathsWithObstacles(vector<vector<int> > &obstacleGrid) {
        if(obstacleGrid.empty() || obstacleGrid[0].empty()) return 0;
        int x = obstacleGrid.size(); int y= obstacleGrid[0].size();
        memset(pathrec,0,sizeof(pathrec));
        int pathnum = findpath(obstacleGrid,0,0,x,y);
        return pathnum;
    }
};