Minimum Path Sum

问题：从左上角到右下角的最小路径和

class Solution {
public:
    int num[300][300];
    int dfs(int x,int y,vector<vector<int> >&grid)
    {
        if(x==grid.size()-1 && y==grid[0].size()-1) return grid[x][y];
        if(num[x][y]) return num[x][y];
        int h1=99999,h2=99999;
        if(x+1<grid.size())  h1=dfs(x+1,y,grid);
        if(y+1<grid[0].size()) h2=dfs(x,y+1,grid);
        return num[x][y]=min(h1,h2)+grid[x][y];
    }
    int minPathSum(vector<vector<int> > &grid) {
        memset(num,0,sizeof(num));
        return dfs(0,0,grid);
    }
};