Submission #617810

#	Time	Username	Problem	Language	Result	Execution time	Memory
617810		Bench0310	Roller Coaster Railroad (IOI16_railroad)	C++17	0 / 100	130 ms	12720 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)
{
    int n=s.size();
    s.push_back((1<<30));
    t.push_back(0);
    vector<array<int,2>> one(n+1);
    for(int i=0;i<=n;i++) one[i]={t[i],i};
    vector<array<int,2>> two(n+1);
    for(int i=0;i<=n;i++) two[i]={s[i],i};
    sort(one.begin(),one.end());
    sort(two.begin(),two.end());
    vector<int> h(n+1,0);
    for(int i=0;i<=n;i++) h[one[i][1]]=i;
    for(int i=0;i<=n;i++)
    {
        one[i][1]=i;
        two[i][1]=h[two[i][1]];
        //~ cout << "[" << one[i][0] << "," << one[i][1] << "] [" << two[i][0] << "," << two[i][1] << "]" << endl;
    }
    vector<int> p(n+1,0);
    for(int i=0;i<=n;i++) p[i]=i;
    vector<int> sz(n+1,1);
    function<int(int)> find_set=[&](int a)->int
    {
        if(a==p[a]) return a;
        else return p[a]=find_set(p[a]);
    };
    int cycles=n+1;
    auto merge_sets=[&](int a,int b)
    {
        a=find_set(a);
        b=find_set(b);
        if(a==b) return;
        cycles--;
        if(sz[a]<sz[b]) swap(a,b);
        p[b]=a;
        sz[a]+=sz[b];
    };
    auto cost=[&](int a,int b)->int{return max(0,one[a][0]-two[b][0]);};
    vector<int> to(n+1,0);
    ll res=0;
    for(int i=0;i<=n;i++)
    {
        merge_sets(i,two[i][1]);
        res+=cost(i,i);
        to[i]=i;
    }
    priority_queue<array<int,2>,vector<array<int,2>>,greater<array<int,2>>> q;
    auto eval=[&](int i)->int
    {
        return (cost(i,to[i+1])+cost(i+1,to[i])-cost(i,to[i])-cost(i+1,to[i+1]));
    };
    for(int i=0;i<n;i++) q.push({eval(i),i});
    while(!q.empty())
    {
        auto [tmp,i]=q.top();
        q.pop();
        //~ cout << "[i=" << i << "], sets: " << find_set(i) << " " << find_set(i+1) << endl;
        if(eval(i)!=tmp) continue;
        if(find_set(i)==find_set(i+1)) continue;
        //~ cout << "process [" << i << ",eval=" << tmp << "]" << endl;
        res+=eval(i);
        merge_sets(i,i+1);
        swap(to[i],to[i+1]);
        if(i-1>=0) q.push({eval(i-1),i-1});
        if(i+2<=n) q.push({eval(i+1),i+1});
    }
    assert(cycles==1);
    return res;
}

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