7-9 红色警报 (25分)

7-9 红色警报 (25分)

#include<iostream>
#include<cstdio>
#include<vector>
#include<algorithm>
#include<cstring>
#include<string>
#include<map>
#include<set>
#include<queue>
#include<iomanip>
#include<stack>
using namespace std;
#define STDIN freopen("in.in", "r", stdin);freopen("out.out", "w", stdout);


const int N = 505;
int n, m;
int fa[N];

void init()
{
    for (int i = 0; i < n; i++) fa[i] = i;
}

int find(int x)
{
    if (x == fa[x]) return x;
    return fa[x] = find(fa[x]);
}
void unite(int a, int b)
{
    int f1 = find(a);
    int f2 = find(b);
    fa[f1] = f2;
}
vector<pair<int,int> > edge;
set<int> city;
vector<string> ans;
vector<int> city2;
map<int, vector<int> > ma;
string change(int j)
{
    if (j == 0) return "0";
    string t = "";
    while (j)
    {
        t += j%10 + '0';
        j/=10;
    }
    reverse(t.begin(), t.end());
    return t;
}

int main()
{
//     STDIN
    cin >> n >> m;
    init();
    for (int i = 1; i <= m; i++) {
        int a, b;
        cin >> a >> b;
        edge.push_back({a, b});
        ma[a].push_back(b);
        ma[b].push_back(a);
    }
    int k;
    cin >> k;
    for (int i = 1; i <= k; i++)
    {
        int t;
        cin >> t;
        city.insert(t);
        city2.push_back(t);
    }
    if (k == n) ans.push_back("Game Over.");
    for (int i = 0; i < m; i++)
    {
        if (city.find(edge[i].first) == city.end() && city.find(edge[i].second) == city.end())
        {
            unite(edge[i].first, edge[i].second);
        }
    }
    reverse(city2.begin(), city2.end());
    for (int i = 0; i < k; i++)
    {
        city.erase(city2[i]);
        int cnt = 0;
        for (auto &j : ma[city2[i]])
        {
            if (city.find(j) == city.end())
            {
                if (find(j) != find(city2[i]))
                {
                    cnt++;        
                    unite(j, city2[i]);
                    
                }
            }
        }
        if (cnt > 1){
            string s = "Red Alert: City ";
            string send = " is lost!";
            string smid = change(city2[i]);
            s += smid + send;
            ans.push_back(s);
        }
        else{
            string s = "City ";
            string send = " is lost.";
            string smid = change(city2[i]);
            s += smid + send;
            ans.push_back(s);
        }
    }
    reverse(ans.begin(), ans.end());
    for (auto &i : ans) cout << i << endl;
    
}