Submission #1040082

#	Time	Username	Problem	Language	Result	Execution time	Memory
1040082		Marco_Escandon	Event Hopping (BOI22_events)	C++11	10 / 100	1593 ms	524288 KiB

events

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll MOD = 1000000007;
const string ny[2] = {"No", "Yes"};
#define x first
#define y second
vector<vector<ll>> G(200000);
ll cmc(ll n,ll a,ll b)
{
    vector<ll> v(n+2, 1e9);
    priority_queue<pair<ll,ll>>q;
    q.push({0,a});
    while(!q.empty())
    {
        pair<ll,ll> a=q.top();q.pop();
        if(v[a.y]==1e9)
        {
            v[a.y]=-a.x;
            if(a.y==b) return -a.x;
            for(auto i:G[a.y])
                if(v[i]==1e9)
                    q.push({a.x-1,i});
        }
    }
    return 1e9;
};
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);cout.tie(0);
    ll n,q;
    cin>>n>>q;
    vector<pair<ll,ll>> cad;
    vector<pair<ll,ll>> input;input.push_back({0,0});
    for(int i=1; i<=n; i++)
    {
        ll a,b;
        cin>>a>>b;
        input.push_back({a,b});
        cad.push_back({a,i});
        cad.push_back({b,i});
    }
    sort(cad.begin(),cad.end());
    set<ll> s;
    for(int i=0; i<cad.size(); i++)
    {
        vector<ll> temp,temp2;
        ll a=i;
        while(i<cad.size()&&cad[a].x==cad[i].x){
            temp.push_back(cad[i].y);
            i++;
        }
        i--;
        for(auto j:temp)
        {
            if(s.find(j)!=s.end())
                temp2.push_back(j);
            else s.insert(j);
        }
        for(auto j:temp2) for(auto k:s) G[j].push_back(k);
        for(auto j:temp2) if(s.find(j)!=s.end()) s.erase(j);
    }
    for(int i=0; i<q; i++)
    {
        ll a,b;
        cin>>a>>b;
        if(input[a].y>input[b].y){ cout<<"impossible"<<"\n"; continue;}
        a=cmc(n,a,b);
        if(a==1e9) cout<<"impossible"<<"\n";
        else cout<<a<<"\n";
    }
    return 0;
}

Compilation message (stderr)

events.cpp: In function 'int main()':
events.cpp:46:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<long long int, long long int>, std::allocator<std::pair<long long int, long long int> > >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   46 |     for(int i=0; i<cad.size(); i++)
      |                  ~^~~~~~~~~~~
events.cpp:50:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<long long int, long long int>, std::allocator<std::pair<long long int, long long int> > >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   50 |         while(i<cad.size()&&cad[a].x==cad[i].x){
      |               ~^~~~~~~~~~~

• Subtask 1: 0 / 10
• Subtask 2: 10 / 10
• Subtask 3: 0 / 15
• Subtask 4: 0 / 15
• Subtask 5: 0 / 20
• Subtask 6: 0 / 30