欢乐的周末

#include <algorithm>
#include <iostream>
#include <unordered_map>
#include <vector>
#include <stack>
#include <sstream>
#include <list>
#include <queue>
using namespace std;

class union_find {
	vector<int> data;
	int __size;
public:
	vector<int> spot;
	vector<int> memb;
	union_find(int n) :__size(n) {
		data.resize(n);
		spot.resize(n);
		memb.resize(n);
		for (int i = 0; i < n; i++) data[i] = i;
	}
	int find(int which) {
		while (which != data[which]) {
			which = data[which];
		}
		return which;
	}
	void merge(int ua, int ub) {
		ua = find(ua), ub = find(ub);
		if (ua < ub) {
			spot[ua] += spot[ub];
			memb[ua] += memb[ub];
			data[ub] = ua;
			__size--;
		}
		else if (ua > ub) {
			spot[ub] += spot[ua];
			memb[ub] += memb[ua];
			data[ua] = ub;
			__size--;
		}
	}
	inline int size() { return __size; }
	void memb_add(int which) {
		which = find(which);
		memb[which]++;
	}
	void spot_add(int which) {
		which = find(which);
		spot[which]++;
	}
};

void achieve(vector<vector<int>> mp) {
	int n = mp.size(), m = mp[0].size();
	union_find unf(n * m);
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < m; j++) {
			if (mp[i][j] == 1)continue;
			if (mp[i][j] == 2) unf.memb_add(i * m + j);
			if (mp[i][j] == 3) unf.spot_add(i * m + j);
			if (i > 0 && mp[i - 1][j] != 1) {
				unf.merge((i - 1) * m + j, i * m + j);
			}
			if (j > 0 && mp[i][j - 1] != 1) {
				unf.merge(i * m + j - 1, i * m + j);
			}
		}
	}
	for (int i = 0; i < unf.size(); i++) {
		if (unf.memb[i] == 2) {
			cout << unf.spot[i];
			return;
		}
	}
	cout << -1;
}
int main() {
	achieve({ 
		{2,1,0,3},
		{0,1,2,1},
		{0,3,0,1},
		{0,1,1,3} });
}