Submission #677126

#	Time	Username	Problem	Language	Result	Execution time	Memory
677126		jamezzz	Towns (IOI15_towns)	C++17	25 / 100	20 ms	476 KiB

towns

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

#define fi first
#define se second
#define pf printf
#define pb push_back
#define sz(x) ((int)x.size())
#define all(x) x.begin(),x.end()
typedef vector<int> vi;
typedef pair<int,int> ii;

int cnt;
map<int,int> memo[150];

inline int ask(int a,int b){
	if(a==b)return 0;
	if(memo[a].find(b)!=memo[a].end())return memo[a][b];
	++cnt;
	return memo[a][b]=memo[b][a]=getDistance(a,b);
}

int hubDistance(int N,int sub){
	cnt=0;
	for(int i=0;i<N;++i)memo[i].clear();
	
	int a=0,b=0,diam=0;
	for(int i=0;i<N;++i)if(ask(a,i)>ask(a,b))b=i;
	for(int i=0;i<N;++i)diam=max(diam,ask(b,i));
	
	int ans=diam;
	
	vector<ii> v;
	for(int i=0;i<N;++i){
		int ab=ask(a,b),ai=ask(a,i),bi=ask(i,b);
		int db=(ab+bi-ai)/2;
		v.pb({db,i});
		
		ans=min(ans,max(db,diam-db));
	}
	
	sort(all(v));
	for(int i=0;i<N;++i){
		if(max(v[i].fi,ask(a,b)-v[i].fi)!=ans)continue;
		int l=i,r=i;
		while(r<N-1&&v[r].fi==v[r+1].fi)++r;
		if(l>N/2||N-r>N/2)continue;
		
		vector<vi> cur,nxt,dead;
		for(int i=l;i<=r;++i)cur.pb({v[i].se});
		
		vi rep={};
		while(!cur.empty()){
			for(int i=0;i<sz(cur);i+=2){
				if(i+1==sz(cur)){
					rep=cur[i];
				}
				else{
					int x=cur[i][0],y=cur[i+1][0];
					if(ask(a,x)+ask(a,y)-ask(x,y)>2*v[l].fi){
						vi tmp;
						for(int x:cur[i])tmp.pb(x);
						for(int x:cur[i+1])tmp.pb(x);
						nxt.pb(tmp);
					}
					else dead.pb(cur[i]),dead.pb(cur[i+1]);
				}
			}
			swap(cur,nxt);
			nxt.clear();
		}
		
		if(rep.empty())return ans;
		
		int num=rep.size();
		for(vi i:dead){
			int x=rep[0],y=i[0];
			if(ask(a,x)+ask(a,y)-ask(x,y)>2*v[l].fi)num+=i.size();
		}
		if(num<=N/2)return ans;
		
		i=r;
		assert(cnt<7*N/2);
	}
	
	return -ans;
}

Compilation message (stderr)

towns.cpp: In function 'int hubDistance(int, int)':
towns.cpp:51:11: warning: declaration of 'i' shadows a previous local [-Wshadow]
   51 |   for(int i=l;i<=r;++i)cur.pb({v[i].se});
      |           ^
towns.cpp:44:10: note: shadowed declaration is here
   44 |  for(int i=0;i<N;++i){
      |          ^
towns.cpp:55:12: warning: declaration of 'i' shadows a previous local [-Wshadow]
   55 |    for(int i=0;i<sz(cur);i+=2){
      |            ^
towns.cpp:44:10: note: shadowed declaration is here
   44 |  for(int i=0;i<N;++i){
      |          ^
towns.cpp:63:15: warning: declaration of 'x' shadows a previous local [-Wshadow]
   63 |       for(int x:cur[i])tmp.pb(x);
      |               ^
towns.cpp:60:10: note: shadowed declaration is here
   60 |      int x=cur[i][0],y=cur[i+1][0];
      |          ^
towns.cpp:64:15: warning: declaration of 'x' shadows a previous local [-Wshadow]
   64 |       for(int x:cur[i+1])tmp.pb(x);
      |               ^
towns.cpp:60:10: note: shadowed declaration is here
   60 |      int x=cur[i][0],y=cur[i+1][0];
      |          ^
towns.cpp:76:19: warning: conversion from 'std::vector<int>::size_type' {aka 'long unsigned int'} to 'int' may change value [-Wconversion]
   76 |   int num=rep.size();
      |           ~~~~~~~~^~
towns.cpp:77:10: warning: declaration of 'i' shadows a previous local [-Wshadow]
   77 |   for(vi i:dead){
      |          ^
towns.cpp:44:10: note: shadowed declaration is here
   44 |  for(int i=0;i<N;++i){
      |          ^
towns.cpp:79:56: warning: conversion from 'std::vector<int>::size_type' {aka 'long unsigned int'} to 'int' may change value [-Wconversion]
   79 |    if(ask(a,x)+ask(a,y)-ask(x,y)>2*v[l].fi)num+=i.size();
      |                                                        ^
towns.cpp:24:27: warning: unused parameter 'sub' [-Wunused-parameter]
   24 | int hubDistance(int N,int sub){
      |                       ~~~~^~~

• Subtask 1: 13 / 13
• Subtask 2: 12 / 12
• Subtask 3: 0 / 13
• Subtask 4: 0 / 10
• Subtask 5: 0 / 13
• Subtask 6: 0 / 39