Submission #1037353

#	Time	Username	Problem	Language	Result	Execution time	Memory
1037353		12345678	Roller Coaster Railroad (IOI16_railroad)	C++17	100 / 100	489 ms	39744 KiB

railroad

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

using namespace std;

const int nx=4e5+5;

int n, T, qs[nx], dsu[nx], rv[nx];
long long ans;
map<int, int> mp;

int find(int x)
{
    if (dsu[x]==x) return x;
    return dsu[x]=find(dsu[x]);
}

long long plan_roller_coaster(std::vector<int> s, std::vector<int> t) {
    n=s.size();
    for (int i=0; i<n; i++) mp[s[i]]=mp[t[i]]=0;
    for (auto &[x, y]:mp) y=++T, rv[y]=x;
    for (int i=1; i<=mp.size(); i++) dsu[i]=i;
    for (int i=0; i<n; i++) qs[mp[s[i]]]++, qs[mp[t[i]]]--, dsu[find(mp[s[i]])]=find(mp[t[i]]);
    for (int i=1; i<mp.size(); i++) 
    {
        qs[i]+=qs[i-1];
        if (qs[i]>1) ans+=(long long)(rv[i+1]-rv[i])*(qs[i]-1), dsu[find(i)]=find(i+1);
        if (qs[i]<1) dsu[find(i)]=find(i+1);
    }
    dsu[find(1)]=find(mp.size());
    priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> pq;
    for (int i=1; i<mp.size(); i++) pq.push({rv[i+1]-rv[i], i});
    while (!pq.empty())
    {
        auto [w, u]=pq.top();
        pq.pop();
        if (find(u)==find(u+1)) continue;
        ans+=w;
        dsu[find(u)]=find(u+1);
    }
    return ans;
}

Compilation message (stderr)

railroad.cpp: In function 'long long int plan_roller_coaster(std::vector<int>, std::vector<int>)':
railroad.cpp:22:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::map<int, int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   22 |     for (int i=1; i<=mp.size(); i++) dsu[i]=i;
      |                   ~^~~~~~~~~~~
railroad.cpp:24:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::map<int, int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   24 |     for (int i=1; i<mp.size(); i++)
      |                   ~^~~~~~~~~~
railroad.cpp:32:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::map<int, int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   32 |     for (int i=1; i<mp.size(); i++) pq.push({rv[i+1]-rv[i], i});
      |                   ~^~~~~~~~~~

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