Submission #670066

#	Time	Username	Problem	Language	Result	Execution time	Memory
670066		alvingogo	Towns (IOI15_towns)	C++14	100 / 100	20 ms	384 KiB

towns

#include <bits/stdc++.h>
#include <towns.h>
#pragma GCC optimize("Ofast")
#define AquA cin.tie(0);ios_base::sync_with_stdio(0);
#define fs first
#define sc second
#define p_q priority_queue
using namespace std;

map<pair<int,int>,int> mp;
int qt=0;
int f(int x,int y){
    if(x==y){
        return 0;
    }
    if(x>y){
        swap(x,y);
    }
    if(mp.find({x,y})!=mp.end()){
        return mp[{x,y}];
    }
    qt++;
    return mp[{x,y}]=getDistance(x,y);
}
int hubDistance(int n,int sub){
    qt=0;
    mp.clear();
    int a=0;
    for(int i=0;i<n;i++){
        if(f(0,i)>f(0,a)){
            a=i;
        }
    }
    int b=a;
    for(int i=0;i<n;i++){
        if(f(a,i)>f(a,b)){
            b=i;
        }
    }
    assert(a!=b);
    map<int,pair<int,vector<int> > > m;
    int dd=(f(0,a)-f(0,b)+f(a,b))/2;
    for(int i=0;i<n;i++){
        if(i!=a){
            int x=min(dd,(f(a,i)-f(0,i)+f(a,0))/2);
            m[x].fs=max(m[x].fs,f(i,a)-x);
            m[x].sc.push_back(i);
        }
    }
    vector<int> g;
    int cz=0;
    for(auto &h:m){
        g.push_back(h.fs);
        cz++;
    }
    int p=g.size();
    vector<int> dis(p,0);
    for(int i=0;i<p;i++){
        dis[i]=max(dis[i],max(g[i],f(a,b)-g[i]));
        dis[i]=max(dis[i],m[g[i]].fs);
        for(int j=i+1;j<p;j++){
            int u=g[j]-g[i];
            dis[i]=max(dis[i],m[g[j]].fs+u);
            dis[j]=max(dis[j],m[g[i]].fs+u);
        }
    }
    int ans=2e9;
    for(int i=0;i<p;i++){
        ans=min(ans,dis[i]);
    }
    int at=-1;
    auto cal=[&](int y){
        vector<int> dis2(n);
        for(int i=0;i<n;i++){
            int x=min(dd,(f(a,i)-f(0,i)+f(a,0))/2);
            dis2[i]=f(a,i)-x+abs(g[y]-x);
        }
        vector<int> vis(n),pp(n);
        int cnt=0,lo=0;
        for(int i=0;i<n;i++){
            if(cnt==0){
                lo=i;
                cnt++;
            }
            else{
                if(f(lo,i)!=dis2[i]+dis2[lo]){
                    cnt++;
                    vis[i]=1;
                    pp[lo]++;
                }
                else{
                    cnt--;
                }
            }
        }
        int cc=0;
        for(int i=0;i<n;i++){
            if(!vis[i]){
                int q=(f(lo,i)!=dis2[i]+dis2[lo]);
                if(q){
                    cc+=pp[i]+1;
                }
            }
        }
        if(cc<=n/2){
            at=1;
        }
    };
    int nw=1;
    int rr=0;
    for(int i=0;i<p;i++){
        int c=m[g[i]].sc.size();
        int u=n-c-nw;
        if(nw<=n/2 && u<=n/2 && dis[i]==ans){
            if(c<=n/2){
                at=1;
                continue;
            }
            rr++;
            cal(i);
        }
        nw+=c;
    }
    assert(rr<=1);
    assert(2*qt<=7*n);
    return ans*at;
}

Compilation message (stderr)

towns.cpp: In function 'int hubDistance(int, int)':
towns.cpp:56:17: warning: conversion from 'std::vector<int>::size_type' {aka 'long unsigned int'} to 'int' may change value [-Wconversion]
   56 |     int p=g.size();
      |           ~~~~~~^~
towns.cpp:112:30: warning: conversion from 'std::vector<int>::size_type' {aka 'long unsigned int'} to 'int' may change value [-Wconversion]
  112 |         int c=m[g[i]].sc.size();
      |               ~~~~~~~~~~~~~~~^~
towns.cpp:25:27: warning: unused parameter 'sub' [-Wunused-parameter]
   25 | int hubDistance(int n,int sub){
      |                       ~~~~^~~

• Subtask 1: 13 / 13
• Subtask 2: 12 / 12
• Subtask 3: 13 / 13
• Subtask 4: 10 / 10
• Subtask 5: 13 / 13
• Subtask 6: 39 / 39