Submission #637100

#	Time	Username	Problem	Language	Result	Execution time	Memory
637100		ggoh	Roller Coaster Railroad (IOI16_railroad)	C++14	30 / 100	136 ms	14784 KiB

railroad

#include<bits/stdc++.h>
#include "railroad.h"
using namespace std;
#define sz(v) ((int)(v).size())
typedef long long lint;
typedef pair<int,int> pii;

int par[200002];
int find(int p)
{
    if(par[p]==p)return p;
    else return par[p]=find(par[p]);
}
void uni(int p,int q)
{
    p=find(p);
    q=find(q);
    if(p!=q)par[p]=q;
}
int v[200002];
int line[200002],sT[200002],num[200002],ori[200002],col;
void dfs(int p)
{
    v[p]=col;
    if(!v[sT[p]])dfs(sT[p]);
}
lint plan_roller_coaster(vector<int> s, vector<int> t) {

    int n = (int) s.size();
    lint ans=0;
    vector<pii>S;
    vector<pii>T;
    for(int i=0;i<n;i++)S.push_back({s[i],i});
    for(int i=0;i<n;i++)T.push_back({t[i],i});
    S.push_back({1e9+1,n});T.push_back({0,n});
    sort(S.begin(),S.end());
    sort(T.begin(),T.end());
    for(int i=0;i<=n;i++)num[T[i].second]=i;
    for(int i=0;i<=n;i++)
    {
        ori[i]=T[i].first;
        if(T[i].first>S[i].first)
        {
            ans+=T[i].first-S[i].first;
            T[i].first=S[i].first;
        }
    }
    int j=0;
    for(int i=0;i<=n;i++)
    {
        while(j<=n && T[i].first>S[j].first)j++;
        line[i]=j;
        sT[i]=num[S[i].second];
    }
    col=0;
    for(int i=0;i<=n;i++)
    {
        if(!v[i])
        {
            col++;
            dfs(i);
        }
    }
    int mini[200002],maxi;
    priority_queue<pii>P;
    for(int i=1;i<=col;i++)par[i]=i;
    for(int i=0;i<=n;)
    {
        int k=i;
        mini[k]=ori[i];
        maxi=T[i].first;
        while(k+1<=n)
        {
            maxi=max(maxi,T[k+1].first);
            if(mini[k]>=maxi){
              k++;
              mini[k]=mini[k-1];
            }
            else break;
        }
        for(int l=i+1;l<=k;l++)uni(v[l],v[l-1]);
        i=k+1;
    }
    for(int i=0;i<=n;i++)
    {
        if(line[i]!=i && find(v[i-1])!=find(v[i]))uni(v[i-1],v[i]);
        if(line[i]==i && i>0)P.push({-(T[i].first-max(mini[i-1],S[i-1].first)),i});
    }
    while(!P.empty())
    {
        pii p=P.top();
        P.pop();
        if(find(v[p.second])!=find(v[p.second-1]))
        {
            uni(v[p.second-1],v[p.second]);
            ans+=(-p.first);
        }
    }
    return ans;
}

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