Submission #927517

#	Time	Username	Problem	Language	Result	Execution time	Memory
927517		12345678	Spring cleaning (CEOI20_cleaning)	C++17	17 / 100	47 ms	12040 KiB

cleaning

#include <bits/stdc++.h>

using namespace std;

const int nx=1e5+5;
int n, q, deg[nx], lvl[nx], u, v, t, res, rt, cnt[nx], lf;
vector<int> d[nx];

void dfs(int u, int p)
{
    lvl[u]=lvl[p]+1;
    if (d[u].size()==1) deg[u]++, lf++;
    for (auto v:d[u]) if (v!=p) dfs(v, u), deg[u]+=deg[v];
    if (deg[u]>2) deg[u]=((deg[u]%2)==1)?1:2;
    if (u!=rt) res+=deg[u];
    if (deg[u]==2&&u!=rt) cnt[u]=1;
}

void dfs2(int u, int p)
{
    for (auto v:d[u]) if (v!=p) cnt[v]+=cnt[u], dfs2(v, u);
}

int main()
{
    cin.tie(NULL)->sync_with_stdio(false);
    cin>>n>>q;
    for (int i=1; i<n; i++) cin>>u>>v, d[u].push_back(v), d[v].push_back(u);
    for (int i=1; i<=n; i++) if (d[i].size()>1) rt=i;
    dfs(rt, rt);
    dfs2(rt, rt);
    while (q--)
    {
        cin>>t>>u;
        if ((lf+(d[u].size()!=1))%2==1) cout<<-1<<'\n';
        else if (d[u].size()==1) cout<<res+1<<'\n';
        else cout<<res+(lvl[u]-2*cnt[u])<<'\n';
    }
}

/*
6 6
1 2
1 3
2 4
2 5
5 6
1 1
1 2
1 3
1 4
1 5
1 6

7
6
-1
-1
7
-1

8 8
5 4
5 6
4 2
4 3
4 1
6 7
7 8
1 1
1 2
1 3
1 4
1 5
1 6
1 7
1 8
*/

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