Submission #825248

#	Time	Username	Problem	Language	Result	Execution time	Memory
825248		vnm06	Roller Coaster Railroad (IOI16_railroad)	C++14	100 / 100	242 ms	55880 KiB

railroad

#include "railroad.h"
#include<bits/stdc++.h>
using namespace std;

struct point
{
    int pos, id, ty;
    point() {}
    point(int a, int b, int c)
    {
        pos=a;
        id=b;
        ty=c;
    }
};

bool cmp(point p, point q)
{
    return p.pos<q.pos;
}

int n;
int poss[200005], post[200005];
vector<int> gr[400005];
point p[400005];
int brt=0;

int tree[400005];

void dfs(int v)
{
    int brs=gr[v].size();
    for(int i=0; i<brs; i++)
    {
        int nv=gr[v][i];
        if(!tree[nv])
        {
            tree[nv]=brt;
            dfs(nv);
        }
    }
}

int par[400005];
int dp[400005];
vector<pair<int, pair<int, int> > > edges;


long long plan_roller_coaster(std::vector<int> s, std::vector<int> t)
{
    s.push_back(1000000005);
    t.push_back(1);
    n=s.size();
    for(int i=0; i<n; i++)
    {
        p[2*i]=point(s[i], i, 1);
        p[2*i+1]=point(t[i], i, -1);
    }
    sort(p, p+2*n, cmp);
    long long ans=0;
    long long sm=0;
    for(int i=0; i<2*n; i++)
    {
        if(p[i].ty==-1) poss[p[i].id]=i;
        if(p[i].ty==1) post[p[i].id]=i;
    }
    for(int i=0; i<n; i++) gr[poss[i]].push_back(post[i]);

    for(int i=0; i<2*n; i++)
    {
        sm+=p[i].ty;
        if(i && p[i].pos==p[i-1].pos) {gr[i-1].push_back(i); gr[i].push_back(i-1);}
        if(sm>0) {ans+=sm*(p[i+1].pos-p[i].pos); gr[i+1].push_back(i); gr[i].push_back(i+1);}
        if(sm<0) {gr[i+1].push_back(i); gr[i].push_back(i+1);}
    }
    for(int i=0; i<2*n; i++)
    {
        if(!tree[i])
        {
            brt++;
            tree[i]=brt;
            dfs(i);
        }
    }
    ///cout<<ans<<endl;
    for(int i=1; i<=brt; i++) {par[i]=i; dp[i]=1;}
    for(int i=0; i<2*n-1; i++)
    {
        if(tree[i]==tree[i+1]) continue;
        edges.push_back({p[i+1].pos-p[i].pos,{tree[i], tree[i+1]}});
    }
    sort(edges.begin(), edges.end());
    int m=edges.size();
    for(int i=0; i<m; i++)
    {
        int v1=edges[i].second.first, v2=edges[i].second.second;
        while(v1!=par[v1]) v1=par[v1];
        while(v2!=par[v2]) v2=par[v2];
        if(v1==v2) continue;
        ans+=edges[i].first;
        if(dp[v1]>dp[v2]) par[v2]=v1;
        else if(dp[v1]<dp[v2]) par[v1]=v2;
        else
        {
            par[v1]=v2;
            dp[v2]++;
        }
    }
    return ans;
}

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