Submission #911272

#	Time	Username	Problem	Language	Result	Execution time	Memory
911272		JakobZorz	Roller Coaster Railroad (IOI16_railroad)	C++17	100 / 100	770 ms	57248 KiB

railroad

#include"railroad.h"
#include<iostream>
#include<map>
#include<set>
#include<algorithm>
using namespace std;
typedef long long ll;

int dsu[500000];
int get(int a){
    if(dsu[a]<0)
        return a;
    return dsu[a]=get(dsu[a]);
}

void merge(int a,int b){
    a=get(a);
    b=get(b);
    if(a==b)
        return;
    if(dsu[a]>dsu[b])
        swap(a,b);
    dsu[a]+=dsu[b];
    dsu[b]=a;
}

ll plan_roller_coaster(vector<int>s,vector<int>t){
    for(int i=0;i<500000;i++)
        dsu[i]=-1;
    s.push_back(1e9);
    t.push_back(1);
    int n=(int)s.size();
    set<int>interestings;
    for(int i:s)
        interestings.insert(i);
    for(int i:t)
        interestings.insert(i);
    vector<int>interesting(interestings.begin(),interestings.end());
    map<int,int>m;
    {
        int idx=0;
        for(int i:interesting)
            m[i]=idx++;
    }
    vector<int>bal(interesting.size());
    for(int&i:s)
        i=m[i];
    for(int&i:t)
        i=m[i];
    for(int i=0;i<n;i++){
        int a=s[i],b=t[i];
        merge(a,b);
        bal[a]++;
        bal[b]--;
    }
    
    ll res=0;
    
    ll cbal=0;
    vector<pair<int,int>>conns;
    for(int i=0;i<(int)interesting.size()-1;i++){
        ll dist=interesting[i+1]-interesting[i];
        conns.emplace_back((int)dist,i);
        cbal+=bal[i];
        res+=max(0LL,cbal*dist);
        if(cbal!=0)
            merge(i,i+1);
    }
    sort(conns.begin(),conns.end());
    for(auto conn:conns){
        if(get(conn.second)!=get(conn.second+1)){
            merge(conn.second,conn.second+1);
            res+=conn.first;
        }
    }
    
    return res;
}

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