Submission #865992

#	Time	Username	Problem	Language	Result	Execution time	Memory
865992		boris_mihov	Spring cleaning (CEOI20_cleaning)	C++17	0 / 100	1088 ms	11612 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 sz[MAXN];
llong sumDist[MAXN];
std::vector <int> g[MAXN];

void dfsSize(int node, int par)
{
    sz[node] = (g[node].size() == 1);
    sumDist[node] = 0;

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

        dfsSize(u, node);
        sz[node] += sz[u];
        sumDist[node] += sumDist[u] + sz[u];
    }
}

llong findCentroid(int node, int par, llong sum)
{
    for (const int &u : g[node])
    {
        if (u == par)
        {
            continue;
        }

        if (sz[u] > sz[1] / 2)
        {
            return findCentroid(u, node, sum + ((sz[1] - sz[u]) - sz[u]));
        }
    }

    return sum;
}

llong calc()
{
    dfsSize(1, 0);
    if (sz[1] & 1) return -1;
    return findCentroid(1, 0, sumDist[1]);
}

int a[MAXN];
void solve()
{  
    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];
            g[a[j]].push_back(++cnt);
            g[cnt].push_back(a[j]);
        }

        std::cout << calc() << '\n';
        for (int j = 1 ; j <= d ; ++j)
        {
            g[a[j]].pop_back();
            g[cnt--].pop_back();
        }
    }
}   

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;
}

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