제출 #972560

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
972560		idas	Event Hopping (BOI22_events)	C++11	0 / 100	414 ms	52304 KiB

events

#include <bits/stdc++.h>
#define FAST_IO ios_base::sync_with_stdio(false); cin.tie(nullptr)
#define FOR(i, begin, end) for(int i=(begin); i<(end); i++)
#define sz(x) int((x).size())
#define pb push_back
#define s second
#define f first

using namespace std;
typedef vector<int> vi;
typedef pair<int, int> pii;
typedef tuple<int, int, int> tiii;

const int INF=1e9;

const int N=5e3+10;
int n, q, s[N], e[N], d[N][N];

set<tiii> st;
void upd_set(int in, int nd, int mn_dist)
{
    auto it=st.lower_bound({in,nd,0});

    if(it==st.end()){
        st.insert({in,nd,mn_dist});
        return;
    }

    int a, b, c; tie(a,b,c)=*it;
    if(a==in && b==nd){
        st.erase(it);
        mn_dist=min(mn_dist, c);
    }

    st.insert({in,nd,mn_dist});
}

vector<pii> inf;
void precalc()
{
    sort(inf.begin(), inf.end(), greater<pii>());

    vi vis;
    while(!inf.empty()){
        int now_end=(inf.back()).f;

        vi ins;
        while(!inf.empty() && (inf.back()).f==now_end){
            pii it=inf.back(); inf.pop_back();
            int in=it.s; ins.pb(in); vis.pb(in);
            st.insert({in,now_end,0});
        }

        for(auto i : ins){
            for(auto x : vis){
                if(i==x) continue;

                auto it=st.lower_bound({x,s[i],0});
                if(it!=st.end()){
                    int in, nd, mn_dist; tie(in, nd, mn_dist)=*it;

                    if(in==x){
                        d[x][i]=min(d[x][i], mn_dist+1);

                        upd_set(in, now_end, d[x][i]);
                    }
                }
            }
        }
    }
}

int main()
{
    FAST_IO;
    cin >> n >> q;
    FOR(i, 0, n)
    {
        cin >> s[i] >> e[i];
        inf.pb({e[i],i});
    }

    FOR(i, 0, n) FOR(j, 0, n) if(i!=j) d[i][j]=INF;

    precalc();

//    FOR(i, 0, n)
//    {
//        FOR(j, 0, n)
//        {
//            cout << i << " " << j << ": " << d[i][j] << '\n';
//        }
//    }

    while(q--){
        int a, b; cin >> a >> b; --a; --b;
        if(d[a][b]==INF){
            cout << "impossible\n";
        }
        else{
            cout << d[a][b] << '\n';
        }
    }
}
/*
2 1
1 4
2 3
1 2

5 2
1 3
2 4
4 7
7 9
3 7
*/

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