QOJ.ac

QOJ

IDProblemSubmitterResultTimeMemoryLanguageFile sizeSubmit timeJudge time
#762081#9570. Binary Treenahida_qaqRE 0ms3600kbC++233.1kb2024-11-19 13:28:352024-11-19 13:28:35

Judging History

你现在查看的是最新测评结果

  • [2024-11-19 13:28:35]
  • 评测
  • 测评结果:RE
  • 用时:0ms
  • 内存:3600kb
  • [2024-11-19 13:28:35]
  • 提交

answer

#include <bits/stdc++.h>
#define int long long
#define io ios::sync_with_stdio(0),cin.tie(0),cout.tie(0)
#define pb push_back
using namespace std;
const int N=1e6+5,mod1=1e9+7,mod2=998244353,inf=1e18;
typedef pair<int,int> pi;
void solve()
{
    int n;
    cin>>n;
    vector<vector<int>>g(n+5);
    for(int i=1;i<=n;i++)
    {
        int x,y;
        cin>>x>>y;
        if(x)
        {
            g[i].pb(x);
            g[x].pb(i);
        }
        if(y)
        {
            g[i].pb(y);
            g[y].pb(i);
        }
    }
    vector<int>size(n+5),weight(n+5);
    vector<int>st(n+5);
    int centroid=1;
    function<void(int,int)>dfs=[&](int u,int fa)
    {
        size[u]=1;
        weight[u]=0;
        for(auto v:g[u])if(!st[v]&&v!=fa)
        {
            dfs(v,u);
            size[u]+=size[v];
            weight[u]=max(weight[u],size[v]);
        }
        weight[u]=max(weight[u],n-size[u]);
        if(weight[u]<=n/2)centroid=u;
    };
    int num=n;
    while(num>1)
    {
        dfs(centroid,0);
        num=size[centroid];
        int du=0;
        for(auto i:g[centroid])if(!st[i])du++;
        if(du==0)
        {
            cout<<'!'<<' '<<centroid<<endl;
            return ;
        }
        if(du==1)
        {
            int x=0;
            for(auto i:g[centroid])if(!st[i])
            {
                x=i;
                break;
            }
            cout<<'?'<<' '<<centroid<<' '<<x<<endl;
            int t;
            cin>>t;
            if(t==0)
            {
                cout<<'!'<<' '<<centroid<<endl;
                return ;
            }
            st[centroid]=1;
            centroid=x;
            continue;
        }
        if(du==2)
        {
            int x=0,y=0;
            for(auto i:g[centroid])if(!st[i])
            {
                if(!x)x=i;
                else
                {
                    y=i;
                    break;
                }
            }
            cout<<'?'<<' '<<x<<' '<<y<<endl;
            int t;
            cin>>t;
            if(t==1)
            {
                cout<<'!'<<' '<<centroid<<endl;
                return ;
            }
            if(t==0)
            {
                st[centroid]=st[y]=1;
                centroid=x;
                continue;
            }
            st[centroid]=st[x]=1;
            centroid=y;
            continue;
        }
        int x=g[centroid][0],y=g[centroid][1],z=g[centroid][2];
        int sx=size[x],sy=size[y],sz=size[z];
        if(sx<sy)swap(x,y),swap(sx,sy);
        if(sx<sz)swap(x,z),swap(sx,sz);
        if(sy<sz)swap(y,z),swap(sy,sz);
        cout<<'?'<<' '<<x<<' '<<y<<endl;
        int t;
        cin>>t;
        if(t==0)
        {
            st[centroid]=st[z]=st[y]=1;
            centroid=x;
            continue;
        }
        if(t==1)
        {
            st[x]=st[y]=1;
            continue;
        }
        st[centroid]=st[z]=st[x]=1;
        centroid=y;
        continue;
    }
}
signed main()
{
    io;
    int t=1;
    cin>>t;
    while(t--)
    {
        solve();
    }
    return 0;
}

Details

Tip: Click on the bar to expand more detailed information

Test #1:

score: 100
Accepted
time: 0ms
memory: 3600kb

input:

2
5
0 0
1 5
2 4
0 0
0 0
2
0
2
0 2
0 0
2

output:

? 1 3
? 3 4
! 3
? 1 2
! 2

result:

ok OK (2 test cases)

Test #2:

score: -100
Runtime Error

input:

5555
8
2 0
8 6
0 0
3 0
0 0
7 0
0 0
5 4
2
2
0
8
0 0
1 4
2 0
0 0
7 8
0 0
3 0
6 0
2
2
2

output:

? 1 8
? 5 4
? 4 3
! 4
? 2 7
? 7 5
? 5 8
? 8 6

result: