Submission #866020

#	Time	Username	Problem	Language	Result	Execution time	Memory
866020		boris_mihov	Spring cleaning (CEOI20_cleaning)	C++17	9 / 100	1062 ms	17444 KiB

cleaning

#include <algorithm>
#include <iostream>
#include <numeric>
#include <cassert>
#include <vector>
#include <queue>
#include <stack>

typedef long long llong;
const int MAXN = 200000 + 10;
const int MOD = 1e9 + 7;
const int INF = 2e9;

int n, q;
int cntEven;
int res[MAXN];
int par[MAXN];
bool was[MAXN];
bool isLeaf[MAXN];
std::vector <int> g[MAXN];

int dfs(int node, int p)
{
    par[node] = p;
    if (g[node].size() == 1)
    {
        isLeaf[node] = true;
        res[node] = 1;
        return 1;
    }

    res[node] = 0;
    for (const int &u : g[node])
    {
        if (u == p)
        {
            continue;
        }

        res[node] ^= dfs(u, node);
    }

    cntEven += !res[node];
    return res[node];
}

void climb(int node)
{
    cntEven -= !res[node];
    res[node] ^= 1;
    cntEven += !res[node];
    if (par[node] != 0)
    {
        climb(par[node]);
    }
}

int a[MAXN];
void solve()
{  
    int root = 1;
    if (g[1].size() == 1) root = g[1][0];
    dfs(root, 0);

    for (int i = 1 ; i <= q ; ++i)
    {
        int d;
        int cnt = n;
        std::cin >> d;
        for (int j = 1 ; j <= d ; ++j)
        {
            std::cin >> a[j];
            if (isLeaf[a[j]] && !was[a[j]]) was[a[j]] = true;
            else climb(a[j]);
        }

        if (res[root] == 1) std::cout << -1 << '\n';
        else std::cout << n + d + cntEven - 2 << '\n';

        for (int j = 1 ; j <= d ; ++j)
        {
            climb(a[j]);
            if (isLeaf[a[j]]) was[a[j]] = false;
        }
    }
}   

void input()
{
    std::cin >> n >> q;
    for (int i = 2 ; i <= n ; ++i)
    {
        int u, v;
        std::cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    }
}

void fastIOI()
{
    std::ios_base :: sync_with_stdio(0);
    std::cout.tie(nullptr);
    std::cin.tie(nullptr);
}

int main()
{
    fastIOI();
    input();
    solve();

    return 0;
}

Compilation message (stderr)

cleaning.cpp: In function 'void solve()':
cleaning.cpp:68:13: warning: unused variable 'cnt' [-Wunused-variable]
   68 |         int cnt = n;
      |             ^~~

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