Submission #1028004

#	Time	Username	Problem	Language	Result	Execution time	Memory
1028004		Dan4Life	Towns (IOI15_towns)	C++17	48 / 100	13 ms	540 KiB

towns

#include "towns.h"
#include <bits/stdc++.h>
using namespace std;
using ar2 = array<int,2>;
const int mxN = 115;
int n, vis[mxN];
int mem[mxN][mxN];
map<int,int> M;

int dis(int a, int b){
	if(a==b) return 0;
	if(mem[a][b]!=-1) return mem[a][b];
	if(mem[b][a]!=-1) return mem[b][a];
	return mem[a][b]=mem[b][a]=getDistance(a,b);
}

int p[mxN], sz[mxN];
int findSet(int i) { return p[i]==i?i:p[i]=findSet(p[i]); }
bool isSameSet(int i, int j) { return findSet(i)==findSet(j); }

void unionSet(int i, int j){
	int x = findSet(i), y = findSet(j);
	if(x==y) return;
	if(sz[x]<sz[y]) swap(x,y);
	p[y]=x; sz[x]+=sz[y];
}

int hubDistance(int N, int sub) {
	n = N; ar2 mx = {0,0};
	int a = 0, b = 0; M.clear();
	memset(mem,-1,sizeof(mem));
	for(int i = 0; i < n; i++) 
		mx=max(mx,{dis(a,i),i});
	a = mx[1]; mx = {0,0};
	for(int i = 0; i < n; i++)
		mx=max(mx,{dis(a,i),i});
	b = mx[1]; 
	int diameter = dis(a,b);
	int ans = diameter;

	for(int i = 0; i < n; i++){
		if(i==a or i==b) continue;
		int branch = (dis(a,i)+dis(b,i)-diameter)/2;
		int lpos = dis(a,i)-branch;
		int rpos = diameter-lpos;
		M[lpos]=max({M[lpos],branch,lpos,rpos});
	}
	for(auto u : M) ans=min(ans,u.second);
	if(sub<=2) return ans;

	for(auto u : M){
		int lpos = u.first, mx_dis = u.second;
		int rpos = diameter-lpos;
		if(mx_dis!=ans) continue; 
		bool ok = 1;
		for(int i = 0; i < n; i++) 
			p[i]=i, sz[i]=1, vis[i]=0;
		for(int i = 0; i < n; i++){
			if(vis[findSet(i)]) continue;
			if(i!=a and i!=b and i!=0) continue;
			int i_u = dis(a,i)-lpos;
			if(dis(a,i)<dis(b,i)) i_u = dis(b,i)-rpos;
			
			for(int j = 0; j < n; j++){
				int u_j = dis(a,j)-lpos;
				if(dis(a,j)<dis(b,j)) u_j = dis(b,j)-rpos;
				if(i_u+u_j != dis(i,j)) unionSet(i,j);
			}
			vis[findSet(i)]=1;
		}
		int x = findSet(a), y = findSet(b), z = findSet(0);
		int tot = sz[x]+sz[y]+sz[z]*(z!=x and z!=y);
		int left = n-tot;
		
		if(sub==4 and max({sz[x],sz[y],sz[z]})>n/2) return -ans;
		if(max({sz[x],sz[y],sz[z],left})<=n/2) return ans;
		if(sub==4) return -ans;
		
		for(int i = 0; i < n; i++) vis[i]=0;
		vis[x]=vis[y]=vis[z]=1;
		for(int i = 0; i < n; i++){
			if(vis[findSet(i)]) continue;
			int i_u = dis(a,i)-lpos;
			if(dis(a,i)<dis(b,i)) i_u = dis(b,i)-rpos;
			for(int j = 0; j < n; j++){
				int u_j = dis(a,j)-lpos;
				if(dis(a,j)<dis(b,j)) u_j = dis(b,j)-rpos;
				if(i_u+u_j != dis(i,j)) unionSet(i,j);
			}
			vis[findSet(i)]=1;
		}
		for(int i = 0; i < n; i++)
			ok&=(sz[findSet(i)]<=n/2);
		if(ok) return ans;
	}
	return -ans;
}

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