Submission #669577

#	Time	Username	Problem	Language	Result	Execution time	Memory
669577		dozer	Spring cleaning (CEOI20_cleaning)	C++14	28 / 100	1090 ms	13136 KiB

cleaning

#include <bits/stdc++.h>
using namespace std;
#define fileio() freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout)
#define fastio() cin.tie(0), ios_base::sync_with_stdio(0)
#define pb push_back
#define sp " "
#define endl "\n"
#define pii pair<int, int>
#define st first
#define nd second
#define N 100005


vector<int> adj[N];
int val[N], par[N], deg[N];
int ans;

int dfs(int node, int root)
{
    int flag = 0;
    par[node] = root;
    for (auto i : adj[node])
    {
        if (i != root) flag ^= dfs(i, node);
    }
    if (adj[node].size() == 1) flag ^= 1;
    val[node] = flag;
    if (flag == 0) val[node] = 2;
    ans += val[node];
    return flag;
}

int32_t main()
{
    fastio();
    int n, q;
    cin>>n>>q;
    for (int i = 1; i < n; i++)
    {
        int u, v;
        cin>>u>>v;
        adj[u].pb(v);
        adj[v].pb(u);
    }

    int flag = dfs(1, 0);
    for (int i = 1; i <= n; i++)
        deg[i] = adj[i].size();
    ans -= val[1];
    //cout<<flag<<sp<<ans<<endl;
    while(q--)
    {
        int d;
        cin>>d;
        vector<int> v;
        for (int i = 0; i < d; i++)
        {
            int node;
            cin>>node;
            if(deg[node] != 1)
            {
                flag ^= 1;
                int curr = node;
                while(curr != 1)
                {
                    ans -= val[curr];
                    val[curr] = 3 - val[curr];
                    ans += val[curr];
                    curr = par[curr];
                }
            }
            deg[node]++;
            v.pb(node);
        }
        
        if (flag) cout<<-1<<endl;
        else cout<<ans + d<<endl;
        
        for (auto node : v)
        {
            deg[node]--;
            if(deg[node] != 1)
            {
                flag ^= 1;
                int curr = node;
                while(curr != 1)
                {
                    ans -= val[curr];
                    val[curr] = 3 - val[curr];
                    ans += val[curr];
                    curr = par[curr];
                }
            }
        }
    }
    
    cerr<<"time taken : "<<(float)clock() / CLOCKS_PER_SEC<<" seconds\n";
}

• Subtask 1: 0 / 0
• Subtask 2: 9 / 9
• Subtask 3: 0 / 9
• Subtask 4: 0 / 16
• Subtask 5: 19 / 19
• Subtask 6: 0 / 17
• Subtask 7: 0 / 30