Submission #1070772

#	Time	Username	Problem	Language	Result	Execution time	Memory
1070772		HorizonWest	Closing Time (IOI23_closing)	C++17	0 / 100	1120 ms	926200 KiB

closing

//#include "closing.h"
#include <iostream>
#include <complex>
#include <iomanip>
#include <vector>
#include <algorithm>
#include <functional>
#include <bitset>
#include <queue>
#include <map>
#include <stack>
#include <cmath>
#include <cstdint>
#include <cassert>
using namespace std;
 
#define ll long long 
#define fs first 
#define sd second 
 
const ll Inf = 1e18 + 7;
 
vector <ll> bfs(int n, int x, vector <vector<pair<ll, ll >>> v)
{
    vector <ll> D(n + 1, Inf); queue <int> q; 
    D[x] = 0; q.push(x); 
 
    while (!q.empty())
    {
        int x = q.front(); q.pop();
 
        for(auto& u : v[x]) if(D[u.fs] == Inf)
        {   
            D[u.fs] = D[x] + u.sd; 
            q.push(u.fs);
        }
    }
    
    return D;
}


vector <int> line(int n, int x, int y, vector <vector<pair<ll, ll>>> v)
{
    vector <int> p(n, -1), s;  
    queue <int> q; q.push(x); p[x] = x;

    x = y = -1;

    for(int i = 0; i < n; i++) if(v[i].size() == 1){
        if(x == -1) x = i;
        else y = i;
    }

    while (!q.empty())
    {
        int x = q.front(); q.pop();
 
        for(auto& u : v[x]) if(p[u.fs] == -1)
        {   
            p[u.fs] = x; 
            q.push(u.fs);
        }
    }

    while (true)
    {
        s.push_back(y);
        if(y == x) break;
        y = p[y];
    }

    reverse(s.begin(), s.end());
    
    return s;
}
 
int max_score(int n, int X, int Y, long long K, vector<int> U, vector<int> V, vector<int> W)
{
    vector <vector<pair<ll, ll>>> v(n + 1,  vector <pair<ll, ll>> ());
 
    for(int i = 0; i < n - 1; i++)
    {
        v[U[i]].push_back({ V[i], W[i] });        
        v[V[i]].push_back({ U[i], W[i] });
    }
    
    vector <ll> d1 = bfs(n, X, v), d2 = bfs(n, Y, v);
    vector <int> s = line(n, X, Y, v); 
    int ans = 0, m = s.size() - 1; 


    for(int i = 0; i <= m; i++)
    { 
        for(int j = m; j >= 0; j--)
        {
            ll t = K; int tmp = 0;  

            priority_queue <pair<ll, pair<ll, ll>>> pq;
            vector <int> p(n);

            for(int k = j; k <= i; k++){
                t -= max(d1[s[k]], d2[s[k]]);
                tmp += 2;
            }

            for(int k = 0; k <= min(i, j-1); k++) if(p[s[k]] == 0){
                t -= d1[s[k]]; p[s[k]] = 1;
                tmp++;
            } else break;

            for(int k = m; k >= max(j, i+1); k--) if(p[s[k]] == 0){
                t -= d2[s[k]]; p[s[k]] = 1;
                tmp++;
            } else break;

            if(t < 0) continue;
            
            p[X] = p[Y] = 0;
            pq.push({ 0, { X, 1}}); 
            pq.push({ 0, { Y, 2} }); //cerr << "NEW: " << tmp << endl;

            while (!pq.empty())
            {
                int x = pq.top().sd.fs, q = pq.top().sd.sd, w = -pq.top().fs; pq.pop();

                if(p[x]) continue;
                p[x] = 1;   //cerr << x << " " << t << " " << w << endl;

                if(t - w >= 0){
                    t -= w;
                    tmp++;
                }

                for(auto& u : v[x]) if(!p[u.fs]){
                    if(q == 1){
                        pq.push({ -d1[u.fs], { u.fs, q }});
                    }
                    else{
                        pq.push({ -d2[u.fs], { u.fs, q }});
                    }
                }        
            }

           // cerr << tmp << endl;

            ans = max(ans, tmp - 2);
        }
    }
 

    return ans;
}

• Subtask 0: 0 / 0
• Subtask 1: 0 / 8
• Subtask 2: 0 / 9
• Subtask 3: 0 / 12
• Subtask 4: 0 / 14
• Subtask 5: 0 / 9
• Subtask 6: 0 / 11
• Subtask 7: 0 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 17