oj.uz

Submission #987635

# Submission time Handle Problem Language Result Execution time Memory
987635 2024-05-23T08:22:21 Z nihon Network (BOI15_net) C++14
0 / 100
 4 ms 14940 KB 
#include <bits/stdc++.h>
#define N 500005
using namespace std;
int n,m,i,j,a,b,t,x,ok,l[N],f[N];
bool r[N];
vector<int> v[N];
vector<pair<int,int>> sol;
bool cmp(int a,int b)
{
    return (v[a][0]<v[b][0])||(v[a][0]==v[b][0] && r[a]>r[b]);
}
int main()
{
    cin>>n;
    for(i=1;i<n;++i)
    {
        cin>>a>>b;
        v[a].push_back(b);
        v[b].push_back(a);
    }
    for(i=2;i<=n;++i)
    {
        if(v[i].size()==1)
        {
            ++t;
            f[t]=i;
            l[i]=t;
        }
    }
    m=v[1].size();
    if(m==1)
    {
        for(i=0;i<m;++i)
        {
            x=v[1][i];
            r[x]=1;
        }
        for(x=1;x<=n;++x)
        {
            if(r[x]) continue;
            if(l[x])
            {
                swap(f[t],f[l[x]]);
                ok=1;
                break;
            }
        }
    }
    sort(f+1,f+t+1,cmp);
    for(i=2;i<=t;)
    {
        if(v[f[i]][0]!=v[f[i-1]][0])
        {
            sol.push_back({f[i],f[i-1]});
            f[i]=f[i-1]=0;
            i+=2;
        }
        else
           i++;
    }
    int st=1,dr=1;
    while(1)
    {
        int ok=0;
        while(!f[st] && st<=n-2) {++st; ok++;}
        if(dr<=st) dr=st+1;
        while(!f[dr] && dr<=n-1) {++dr; ok++;}
        if(ok<2) break;
        if(f[st] && f[dr])
        {
            sol.push_back({f[st],f[dr]});
            f[st]=f[dr]=0;
        }
    }
    if(ok && (m&1))
    {
        sol.push_back({1,f[t]});
    }
    m=sol.size();
    cout<<m<<'\n';
    for(i=0;i<m;++i)
    {
        cout<<sol[i].first<<' '<<sol[i].second<<'\n';
    }
    return 0;
}

Subtask #1
0 / 18.0

# Verdict Execution time Memory Grader output
1 Incorrect 4 ms 14940 KB Invalid number of links.
2 Halted 0 ms 0 KB -

Subtask #2
0 / 45.0

# Verdict Execution time Memory Grader output
1 Incorrect 4 ms 14940 KB Invalid number of links.
2 Halted 0 ms 0 KB -

Subtask #3
0 / 37.0

# Verdict Execution time Memory Grader output
1 Incorrect 4 ms 14940 KB Invalid number of links.
2 Halted 0 ms 0 KB -