Submission #316104

#	Time	Username	Problem	Language	Result	Execution time	Memory
316104		moonrabbit2	Roller Coaster Railroad (IOI16_railroad)	C++17	100 / 100	346 ms	53736 KiB

railroad

#include "railroad.h"
#include <bits/stdc++.h>
#define N 500005
#define x first
#define y second
using namespace std;
typedef long long ll;
typedef pair<int,int> P;
struct edge{ll c;int u,v;};
int n,c,group[N],c_g,p[N],en,x;
ll ans,sum[N],from[N];
vector<int> vec;
vector<int> g1[N];
edge g2[N];
int fi(int x)
{
    if(p[x]==x)
        return x;
    return p[x]=fi(p[x]);
}
void un(int x,int y)
{
    x=fi(x),y=fi(y);
    if(x==y)
        return;
    p[y]=x;
}
void dfs(int curr)
{
    group[curr]=c_g;
    for(auto &it : g1[curr]){
        if(!group[it])
            dfs(it);
    }
}
bool sortf(edge e1,edge e2){return e1.c<e2.c;}
ll plan_roller_coaster(vector<int> s,vector<int> t)
{
    n=s.size();
    for(int i=0;i<n;i++){
		vec.emplace_back(s[i]);
		vec.emplace_back(t[i]);
    }
	vec.emplace_back(1);
	sort(vec.begin(),vec.end()); vec.erase(unique(vec.begin(),vec.end()),vec.end());
	c=vec.size();
	for(int i=1;i<=c;i++) from[i]=vec[i-1];
	for(int i=0;i<n;i++){
		s[i]=lower_bound(vec.begin(),vec.end(),s[i])-vec.begin()+1;
		t[i]=lower_bound(vec.begin(),vec.end(),t[i])-vec.begin()+1;
	}
    sum[2]--;
    g1[c].push_back(1);
    for(int i=0;i<n;i++){
		sum[s[i]+1]++;
		sum[t[i]+1]--;
		g1[s[i]].emplace_back(t[i]);
    }
    for(int i=2;i<=c;i++){
        sum[i]+=sum[i-1];
        if(sum[i]<0)
            g1[i-1].push_back(i);
        if(sum[i]>0){
            g1[i].push_back(i-1);
            ans+=sum[i]*(from[i]-from[i-1]);
        }
    }
    for(int i=1;i<=c;i++){
        if(group[i])
            continue;
        c_g++;
        p[c_g]=c_g;
        dfs(i);
    }
    for(int i=2;i<=c;i++){
        if(group[i-1]!=group[i]){
            g2[++en]={from[i]-from[i-1],group[i-1],group[i]};
        }
    }
    sort(g2+1,g2+1+en,sortf);
    for(int i=1;i<=en;i++){
        int u=g2[i].u,v=g2[i].v;
        if(fi(u)==fi(v))
            continue;
        ans+=g2[i].c;
        un(u,v);
    }
    return ans;
}

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