Submission #1021160

#	Time	Username	Problem	Language	Result	Execution time	Memory
1021160		vjudge1	Roller Coaster Railroad (IOI16_railroad)	C++17	100 / 100	176 ms	64704 KiB

railroad

#include "railroad.h"
#include <bits/stdc++.h>

#define ll long long
#define pii pair<int,int>
#define F first
#define S second
#define sz(s) (int)s.size()
#define in insert
#define pb push_back
#define all(v) v.begin(),v.end()
#define mem(a,i) memset(a,i,sizeof(a))
#define lb lower_bound

using namespace std;

const int MAX=2e5+10;
const ll inf=1e18;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

int n;
vector<int> g[MAX*10];
int bal[10*MAX];

struct DSU{
    int f[10*MAX];

    void init(int n){
        for(int i=0;i<=n;i++)f[i]=i;
    }

    int get(int v){
        return (f[v]==v?v:f[v]=get(f[v]));
    }

    void unite(int u,int v){
        u=get(u);
        v=get(v);
        if(rng()%2)swap(u,v);
        f[u]=v;
    }
}D;

long long plan_roller_coaster(vector<int> s, vector<int> t) {
    vector<int> vec;
    n=sz(s);
    for(int i=0;i<n;i++)vec.pb(s[i]);
    for(int i=0;i<n;i++)vec.pb(t[i]);
    sort(all(vec));
    vec.erase(unique(all(vec)),vec.end());
    for(int i=0;i<n;i++){
        s[i]=lb(all(vec),s[i])-vec.begin();
        t[i]=lb(all(vec),t[i])-vec.begin();
    }
    D.init(sz(vec));
    for(int i=0;i<n;i++){
        D.unite(s[i],t[i]);
    }
    ll ans=0;
    for(int i=0;i<n;i++){
        if(s[i]<t[i]){
            bal[s[i]]++;
            bal[t[i]]--;
        }
        else{
            bal[t[i]]--;
            bal[s[i]]++;
        }
    }
    for(int i=1;i<sz(vec);i++){
        bal[i]+=bal[i-1];
    }
    D.unite(0,sz(vec));
    for(int i=0;i<sz(vec);i++){
        bal[i]--;
    }
    vector<pair<int,pii>> edges;
    for(int i=0;i<sz(vec);i++){
        if(bal[i]==0){
            edges.pb({vec[i+1]-vec[i],{i,i+1}});
        }
        else{
            if(bal[i]>0)ans+=bal[i]*1ll*(vec[i+1]-vec[i]);
            D.unite(i,i+1);
        }
    }
    sort(all(edges));
    for(auto [a,b]:edges){
        if(D.get(b.F)!=D.get(b.S)){
            D.unite(b.F,b.S);
            ans+=a;
        }
    }
    return ans;
}

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