Submission #676998

#	Time	Username	Problem	Language	Result	Execution time	Memory
676998		jamezzz	Towns (IOI15_towns)	C++17	13 / 100	16 ms	420 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;

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];
	return memo[a][b]=memo[b][a]=getDistance(a,b);
}

int hubDistance(int N,int sub){
	for(int i=0;i<N;++i)memo[i].clear();
	
	int a=0,b=0;
	for(int i=0;i<N;++i)if(ask(0,i)>ask(0,a))a=i;
	for(int i=0;i<N;++i)if(ask(a,i)>ask(a,b))b=i;
	
	int ans=ask(a,b);
	
	vector<pair<int,ii>> v;
	for(int i=0;i<N;++i){
		int ab=ask(a,b),ai=ask(a,i),bi=ask(b,i);
		int da=(ab+ai-bi)/2;
		int di=ai-da;
		v.pb({da,{di,i}});
		
		ans=min(ans,max(da,ab-da));
	}
	
	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<ii> cur,nxt;
		for(int i=l;i<=r;++i)cur.pb(v[i].se);
		
		int rep=-1;
		while(!cur.empty()){
			for(int i=0;i<sz(cur);i+=2){
				if(i+1==sz(cur)){
					rep=cur[i].se;
				}
				else{
					int x=cur[i].se,y=cur[i+1].se;
					if(ask(a,x)+ask(a,y)-ask(x,y)>2*v[l].fi){
						nxt.pb(cur[i]);
					}
				}
			}
			swap(cur,nxt);
			nxt.clear();
		}
		
		if(rep==-1)return ans;
		
		int num=0;
		for(int i=l;i<=r;++i){
			int x=rep,y=i;
			if(ask(a,x)+ask(a,y)-ask(x,y)>2*v[l].fi)++num;
		}
		if(num<=N/2)return ans;
	}
	
	return -ans;
}

Compilation message (stderr)

towns.cpp: In function 'int hubDistance(int, int)':
towns.cpp:49:11: warning: declaration of 'i' shadows a previous local [-Wshadow]
   49 |   for(int i=l;i<=r;++i)cur.pb(v[i].se);
      |           ^
towns.cpp:42:10: note: shadowed declaration is here
   42 |  for(int i=0;i<N;++i){
      |          ^
towns.cpp:53:12: warning: declaration of 'i' shadows a previous local [-Wshadow]
   53 |    for(int i=0;i<sz(cur);i+=2){
      |            ^
towns.cpp:42:10: note: shadowed declaration is here
   42 |  for(int i=0;i<N;++i){
      |          ^
towns.cpp:71:11: warning: declaration of 'i' shadows a previous local [-Wshadow]
   71 |   for(int i=l;i<=r;++i){
      |           ^
towns.cpp:42:10: note: shadowed declaration is here
   42 |  for(int i=0;i<N;++i){
      |          ^
towns.cpp:22:27: warning: unused parameter 'sub' [-Wunused-parameter]
   22 | int hubDistance(int N,int sub){
      |                       ~~~~^~~

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