Submission #618120

#	Time	Username	Problem	Language	Result	Execution time	Memory
618120		Bench0310	Roller Coaster Railroad (IOI16_railroad)	C++17	100 / 100	614 ms	40100 KiB

railroad

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

using namespace std;
typedef long long ll;

ll plan_roller_coaster(vector<int> s,vector<int> t)
{
    s.push_back(1<<30);
    t.push_back(1);
    int n=s.size();
    map<int,int> h;
    vector<int> x;
    for(int y:s) x.push_back(y);
    for(int y:t) x.push_back(y);
    sort(x.begin(),x.end());
    x.erase(unique(x.begin(),x.end()),x.end());
    int m=x.size();
    for(int i=0;i<m;i++) h[x[i]]=i;
    vector<int> d(m,0);
    vector<int> p(m,0);
    for(int i=0;i<m;i++) p[i]=i;
    vector<int> sz(m,1);
    function<int(int)> find_set=[&](int a)->int
    {
        if(a==p[a]) return a;
        else return p[a]=find_set(p[a]);
    };
    auto merge_sets=[&](int a,int b)->int
    {
        a=find_set(a);
        b=find_set(b);
        if(a==b) return 0;
        if(sz[a]<sz[b]) swap(a,b);
        p[b]=a;
        sz[a]+=sz[b];
        return 1;
    };
    for(int i=0;i<n;i++)
    {
        int l=h[s[i]];
        int r=h[t[i]];
        d[l]++;
        d[r]--;
        merge_sets(l,r);
    }
    ll res=0;
    int sum=0;
    vector<array<int,3>> edges;
    for(int i=0;i+1<m;i++)
    {
        sum+=d[i];
        res+=(max(0,sum)*ll(x[i+1]-x[i]));
        edges.push_back({x[i+1]-x[i],i,i+1});
        if(sum!=0) merge_sets(i,i+1);
    }
    sort(edges.begin(),edges.end());
    for(auto [c,a,b]:edges) res+=(merge_sets(a,b)*c);
    return res;
}

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