Leetcode-5215 Path with Maximum Gold(黄金矿工)

typedef long long ll;
typedef pair<int,int> P;
#define _for(i,a,b) for(register int i = (a);i < b;i ++)
#define _rep(i,a,b) for(register int i = (a);i > b;i --)
#define INF 0x3f3f3f3f
#define MOD 100000000
#define maxn 10003

const int dx[] = {1,-1,0,0};
const int dy[] = {0,0,1,-1};
class Solution
{
    public:
        
        int vis[100][100];
        vector<vector<int>> v;
        int ans = 0;
        bool valid(int x,int y)
        {
            return x>=0 && x<v.size() && y>=0 && y<v[0].size();
        }
        void dfs(int x,int y,int get)
        {
            ans = max(ans,get);
            _for(i,0,4)
            {
                int nx = x+dx[i];
                int ny = y+dy[i];
                if(valid(nx,ny) && !vis[nx][ny] && v[nx][ny])
                {
                    vis[nx][ny] = 1;
                    dfs(nx,ny,get+v[nx][ny]);
                    vis[nx][ny] = 0;
                }
            }
        }
        int getMaximumGold(vector<vector<int>>& grid)
        {
            v = grid;
            _for(i,0,grid.size())
                _for(j,0,grid[i].size())
                    if(v[i][j])
                    {
                        memset(vis,0,sizeof(vis));
                        vis[i][j] = 1;
                        dfs(i,j,v[i][j]);
                    }
            return ans;
        }
};