Submission #20750

#	Time	Username	Problem	Language	Result	Execution time	Memory
20750		ainta	Roller Coaster Railroad (IOI16_railroad)	C++14	100 / 100	279 ms	24408 KiB

railroad

#include "railroad.h"
#include <stdio.h>
#include <algorithm>
#include <vector>
using namespace std;
int n, X[410000], cnt, Ideg[410000], Odeg[410000], P[410000];
bool v[410000];
int UF[410000];
struct Edge{
    int a, b, c;
    bool operator<(const Edge &p)const{
        return c<p.c;
    }
}w[410000];
int Find(int a){
    if(a==UF[a])return a;
    return UF[a] = Find(UF[a]);
}
void Merge(int a, int b){
    a=Find(a),b=Find(b);
    if(a!=b)UF[a]=b;
}
void Add(int a, int b, int c){
    if(c<=0)return;
    Odeg[a]+=c, Ideg[b]+=c;
    Merge(a,b);
}
long long plan_roller_coaster(vector<int> s, vector<int> t) {
    n = s.size();
    int i;
    for(i=0;i<n;i++){
        X[++cnt] = s[i];
        X[++cnt] = t[i];
    }
    X[++cnt] = 0, X[++cnt] = 2e9;
    sort(X+1,X+cnt+1);
    for(i=1;i<=cnt;i++)UF[i] = i;
    for(i=0;i<n;i++){
        s[i] = lower_bound(X+1,X+cnt+1,s[i])-X;
        t[i] = lower_bound(X+1,X+cnt+1,t[i])-X;
        Add(s[i],t[i],1);
    }
    Add(cnt,1,1);
    int sum = 0;
    long long res = 0;
    for(i=1;i<=cnt;i++){
        sum += Ideg[i] - Odeg[i];
        P[i] = -sum;
        if(sum < 0){
            res += 1ll * (-sum) * (X[i+1]-X[i]);
        }
    }
    for(i=1;i<cnt;i++){
        Add(i+1,i,P[i]);
    }
    for(i=1;i<cnt;i++){
        Add(i,i+1,Ideg[i]-Odeg[i]);
        w[i].a=i,w[i].b=i+1,w[i].c=X[i+1]-X[i];
    }
    sort(w+1,w+cnt);
    for(i=1;i<cnt;i++){
        if(Find(w[i].a)!=Find(w[i].b)){
            res += w[i].c;
            Merge(w[i].a,w[i].b);
        }
    }
    return res;
}

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