Submission #815074

#	Time	Username	Problem	Language	Result	Execution time	Memory
815074		Acanikolic	Dreaming (IOI13_dreaming)	C++14	14 / 100	150 ms	19492 KiB

dreaming

#include <bits/stdc++.h>
		 				
#include "dreaming.h"		 				
		 				 
#define pb push_back 
		
//#define int long long 		
		
#define F first
		 
#define S second
		 
using namespace std;
		 
const int N = 1e5+10;
		 
const int mod = 1e9+7;
		 
const int inf = 1e18;	

vector<pair<int,int>>g[N];
vector<int>all,dist(N),vis(N);

void dfs(int x,int par) {
	all.pb(x);
	for(auto X:g[x]) {
		if(X.F != par) {
			dist[X.F] = dist[x] + X.S;
			dfs(X.F,x);
		}
	}
}

pair<int,int>nadji_precnik(int root) {
	int x,y;
	all.clear();
	dist[root] = 0;
	dfs(root,0);
	int mx = 0,idx = -1;
	for(auto X:all) {
		if(dist[X] >= mx) {
			mx = dist[X];
			idx = X;
		}
	}
	x = idx;
	mx = 0,idx = -1;
	all.clear();
	dist[x] = 0;
	dfs(x,0);
	for(auto X:all) {
		//cout << "X = " << X << " dist[x] = " << dist[X] << endl;
		if(dist[X] >= mx) {
			mx = dist[X];
			idx = X;
		}
	}
	//cout << endl;
	//cout << idx << endl;
	y = idx;
	//if(root == 4) cout << "x = " << x << " y = " << y << endl;
	return {x,y};
}

void obelezi(int x) {
	if(vis[x]) return;
	vis[x] = 1;
	for(auto X:g[x]) obelezi(X.F);
}

int travelTime(int N,int M,int L,int A[],int B[],int T[]) {
	for(int i=0;i<M;i++) {
		g[A[i]].pb({B[i],T[i]});
		g[B[i]].pb({A[i],T[i]});
	}
	vector<int>centers;
	for(int i=0;i<N;i++) {
		if(vis[i]) continue;
		//cout << i << endl;
		all.clear();
		dfs(i,0);
		vector<int>all_in_comp = all;
		pair<int,int>dia = nadji_precnik(i);
		int X = dia.F,Y = dia.S;
		//if(i == 4) cout << X << ' ' << Y << endl;
		dist[X] = 0;
		dfs(X,0);
		map<int,int>D;
		for(auto XX:all_in_comp) D[XX] = dist[XX];
		dist[Y] = 0;
		dfs(Y,0);
		for(auto XX:all_in_comp) D[XX] = max(D[XX],dist[XX]);
		int mn = 1e9,idx = -1;
		for(auto XX:all_in_comp) {
			if(D[XX] < mn) {
				mn = D[XX];
				idx = XX;
			}
		}
		//cout << "root = " << i << " dia = " << X << " " << Y << endl;
		//cout << "root = " << i << " center = " << idx << endl;
		centers.pb(idx);
		obelezi(i);
	}
	for(int i=1;i<centers.size();i++) {
		g[centers[i-1]].pb({centers[i],L});
		g[centers[i]].pb({centers[i-1],L});
	}
	pair<int,int> res = nadji_precnik(1);
	dist[res.F] = 0;
	dfs(res.F,0);
	int index = 0;
	for(int i=0;i<N;i++) {
		if(dist[index] <= dist[i]) index = i;
	}
	return dist[index];
}
				
/*signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
	
	int n,m,l;
	cin >> n >> m >> l;
	vector<int>a(m),b(m),c(m);
	for(int i=0;i<m;i++) cin >> a[i];
	for(int i=0;i<m;i++) cin >> b[i];
	for(int i=0;i<m;i++) cin >> c[i];
	cout << travelTime(n,m,l,a,b,c);
    return 0; 
}*/

Compilation message (stderr)

dreaming.cpp:19:17: warning: overflow in conversion from 'double' to 'int' changes value from '1.0e+18' to '2147483647' [-Woverflow]
   19 | const int inf = 1e18;
      |                 ^~~~
dreaming.cpp: In function 'int travelTime(int, int, int, int*, int*, int*)':
dreaming.cpp:105:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  105 |  for(int i=1;i<centers.size();i++) {
      |              ~^~~~~~~~~~~~~~~

• Subtask 1: 14 / 14
• Subtask 2: 0 / 10
• Subtask 3: 0 / 23
• Subtask 4: 0 / 18
• Subtask 5: 0 / 12
• Subtask 6: 0 / 23