이 제출은 이전 버전의 oj.uz에서 채점하였습니다. 현재는 제출 당시와는 다른 서버에서 채점을 하기 때문에, 다시 제출하면 결과가 달라질 수도 있습니다.
#include<bits/stdc++.h>
#define ll long long
#define ld long double
#define st string
#define fr first
#define se second
const ll mod=1e9+7;
using namespace std;
set<pair<ll, ll> > a;
vector<pair<ll, vector<ll> > > v;
map<ll, ll> us;
int main()
{
    //freopen("1.txt", "r", stdin);
    //freopen("1.txt", "w", stdout);
    ios_base::sync_with_stdio(0);
    cin.tie(NULL);
    cout.tie(NULL);
    ll n, k, s=0, f;
    cin>>n>>k;
    for(ll i=1; i<=n; i++)
    {
        ll x;
        cin>>x;
        us[x]++;
        a.insert({x, i});
        f=x;
        s+=x;
    }
    if(us[f]!=n)
    {
        f=1;
    }
    if(s%k!=0)
    {
        cout<<-1;
        return 0;
    }
    while(a.size()>=k)
    {
        std::vector<ll> q;
        std::vector<pair<ll, ll> > y;
        for(ll i=1; i<=k; i++)
        {
            //cout<<i<<" "<<a.size()<<endl;
            std::pair<ll, ll> x;
            x=*a.rbegin();
            a.erase(*a.rbegin());
            q.push_back(x.se);
            x.fr-=f;
            if(x.fr)
                y.push_back(x);
        }
        for(ll i=0; i<y.size(); i++)
        {
            a.insert(y[i]);
            //cout<<"y="<<y[i].fr<<" "<<y[i].se<<endl;
        }
        v.push_back({f, q});
    }
    if(a.size()>0)
    {
        cout<<-1;
        return 0;
    }
    cout<<v.size()<<endl;
    for(ll i=0; i<v.size(); i++)
    {
        cout<<v[i].fr<<" ";
        for(ll j=0; j<v[i].se.size(); j++)
        {
            cout<<v[i].se[j]<<" ";
        }
        cout<<endl;
    }
    return 0;
}
/*
*/
컴파일 시 표준 에러 (stderr) 메시지
nicegift.cpp: In function 'int main()':
nicegift.cpp:48:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     while(a.size()>=k)
           ~~~~~~~~^~~
nicegift.cpp:68:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(ll i=0; i<y.size(); i++)
                     ~^~~~~~~~~
nicegift.cpp:84:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(ll i=0; i<v.size(); i++)
                 ~^~~~~~~~~
nicegift.cpp:87:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(ll j=0; j<v[i].se.size(); j++)
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