Submission #684468

#	Time	Username	Problem	Language	Result	Execution time	Memory
684468		dsyz	Hotspot (NOI17_hotspot)	C++17	100 / 100	734 ms	1516 KiB

hotspot

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = double;
#define MAXN (1000005)
int main(){
	ios_base::sync_with_stdio(false);cin.tie(0);
	ll N,M;
	cin>>N>>M;
	vector<ll> v[N];
	for(ll i = 0;i < M;i++){
		ll a,b;
		cin>>a>>b;
		v[a].push_back(b);
		v[b].push_back(a);
	}
	ll K;
	cin>>K;
	queue<ll> q;
	ld ans[N];
	memset(ans,0,sizeof(ans));
	pair<ll,ll> dist1[N];
	pair<ll,ll> dist2[N];
	for(ll person = 0;person < K;person++){
		ll A,B;
		cin>>A>>B;
		for(ll i = 0;i < N;i++) dist1[i] = {1e9 + 5,0};
		q.push(A);
		dist1[A] = {0,1};
		while(!q.empty()){
			ll x = q.front();
			q.pop();
			for(auto u : v[x]){
				if(dist1[x].first + 1 < dist1[u].first){
					q.push(u);
					dist1[u] = {dist1[x].first + 1,dist1[x].second};
				}else if(dist1[x].first + 1 == dist1[u].first){
					dist1[u].second += dist1[x].second;
				}
			}
		}
		
		for(ll i = 0;i < N;i++) dist2[i] = {1e9 + 5,0};
		q.push(B);
		dist2[B] = {0,1};
		while(!q.empty()){
			ll x = q.front();
			q.pop();
			for(auto u : v[x]){
				if(dist2[x].first + 1 < dist2[u].first){
					q.push(u);
					dist2[u] = {dist2[x].first + 1,dist2[x].second};
				}else if(dist2[x].first + 1 == dist2[u].first){
					dist2[u].second += dist2[x].second;
				}
			}
		}
		
		for(ll i = 0;i < N;i++){
			if(dist1[i].first + dist2[i].first == dist1[B].first){
				ans[i] += ld(dist1[i].second * dist2[i].second) / ld(dist1[B].second);
			}
		}
	}
	ld maximum = -1e18;
	ll index = 0;
	for(ll i = 0;i < N;i++){
		if(ans[i] > maximum){
			maximum = ans[i];
			index = i;
		}
	}
	cout<<index<<'\n';
}

• Subtask 1: 4 / 4
• Subtask 2: 5 / 5
• Subtask 3: 11 / 11
• Subtask 4: 18 / 18
• Subtask 5: 26 / 26
• Subtask 6: 36 / 36