Submission #573052

#	Time	Username	Problem	Language	Result	Execution time	Memory
573052		2fat2code	Roller Coaster Railroad (IOI16_railroad)	C++17	0 / 100	933 ms	102384 KiB

railroad

#include "railroad.h"
#include <bits/stdc++.h>
#define fr first
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#define sc second
#define all(s) s.begin(), s.end()
#define rc(s) return cout << s, 0
using namespace std;

const int nmax = 400005;

int n, par[nmax], viz[nmax], componente, ans;
unordered_map<int,vector<int>>mp_in;
unordered_map<int,vector<int>>mp_out;
vector<int>compress;
vector<pair<int,pair<int,int>>>edges;

void dfs(int s){
    //cout << "CHECK " << s << ' ' << componente << '\n';
    viz[s] = componente;
    for(auto it : mp_out[compress[s]]){
        auto it2 = lower_bound(all(compress), it) - compress.begin();
        if(!viz[it2]) dfs(it2);
    }
}

int findpar(int x){
    if(x != par[x]){
        par[x] = findpar(par[x]);
    }
    return par[x];
}

long long plan_roller_coaster(vector<int> s, vector<int> t) {
    s.push_back(2 * 1e9);
    t.push_back(1);
    n = (int)s.size();
    for(int i=0;i<n;i++){
        mp_out[s[i]].push_back(t[i]);
        mp_in[t[i]].push_back(s[i]);
        compress.push_back(s[i]);
        compress.push_back(t[i]);
    }
    sort(all(compress));
    compress.resize(unique(all(compress)) - compress.begin());
    int gratis = 0, cu_plata = 0;
    for(int i=0;i<(int)compress.size();i++){
        auto it = compress[i];
        if(gratis > 0) mp_out[compress[i-1]].push_back(compress[i]);
        if(cu_plata > 0) mp_out[compress[i]].push_back(compress[i-1]);
        ans += cu_plata * (compress[i] - compress[i - 1]);
        int x = mp_out[it].size() - mp_in[it].size();
        if(x > 0){
            int lol = min(gratis, x);
            gratis -= lol;
            x -= lol;
            cu_plata += x;
        }
        else if(x < 0){
            int y = abs(x);
            int lol = min(y, cu_plata);
            cu_plata -= lol;
            y -= lol;
            gratis += y;
        }
    }
    for(int i=0;i<(int)compress.size();i++){
        if(!viz[i]){
            ++componente;
            dfs(i);
        }
    }
    for(int i=1;i<=componente;i++) par[i] = i;
    for(int i=1;i<(int)compress.size();i++){
        edges.push_back({compress[i] - compress[i-1], {viz[i-1], viz[i]}});
    }
    sort(all(edges));
    for(auto it : edges){
        int x = findpar(it.sc.fr);
        int y = findpar(it.sc.sc);
        if(x != y){
            ans += it.fr;
            par[x] = y;
        }
    }
    return ans;
}

// 1. Solve the problem
// 2. ???
// 3. Profit

• Subtask 1: 0 / 11
• Subtask 2: 0 / 23
• Subtask 3: 0 / 30
• Subtask 4: 0 / 36