Submission #962129

#	Time	Username	Problem	Language	Result	Execution time	Memory
962129		Ahmed57	Roller Coaster Railroad (IOI16_railroad)	C++17	100 / 100	944 ms	79256 KiB

railroad

#include<bits/stdc++.h>
using namespace std;
#include "railroad.h"
#define int long long
int pr[400001];
int find(int x){
    if(x==pr[x])return x;
    return pr[x] = find(pr[x]);
}
bool mergegroup(int a,int b){
    a = find(a); b = find(b);
    if(a==b)return 0;
    pr[a] = b;
    return 1;
}
long long plan_roller_coaster(vector<int32_t> s, vector<int32_t> t){
    set<int> ss;
    for(auto i:s)ss.insert(i);
    for(auto i:t)ss.insert(i);
    map<int,int> sav;
    int rev[s.size()+t.size()+1];
    int cnt = 0;
    for(auto i:ss){
        sav[i] = ++cnt;
        rev[cnt] = i;
    }
    int in[cnt+1] = {0};
    int out[cnt+1] = {0};
    for(int i = 1;i<=cnt;i++)pr[i] = i;
    for(int i = 0;i<s.size();i++){
        in[sav[s[i]]]++;
        out[sav[t[i]]]++;
        mergegroup(sav[s[i]],sav[t[i]]);
    }
    in[cnt]++;
    out[1]++;
    mergegroup(1,cnt);
    long long ans = 0;
    vector<array<int,3>> ed;
    for(int i = cnt;i>1;i--){
        if(out[i]>in[i]){
            ans+=(out[i]-in[i])*(rev[i]-rev[i-1]);
            out[i-1]+=(out[i]-in[i]);
            mergegroup(i,i-1);
        }else if(in[i]>out[i]){
            in[i-1]+=(in[i]-out[i]);
            mergegroup(i,i-1);
        }
        ed.push_back({rev[i]-rev[i-1],i,i-1});
    }
    sort(ed.begin(),ed.end());
    for(auto i:ed){
        if(mergegroup(i[1],i[2]))ans+=i[0];
    }
    return ans;
}

Compilation message (stderr)

railroad.cpp: In function 'long long int plan_roller_coaster(std::vector<int>, std::vector<int>)':
railroad.cpp:30:20: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   30 |     for(int i = 0;i<s.size();i++){
      |                   ~^~~~~~~~~

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