Submission #90178

#	Time	Username	Problem	Language	Result	Execution time	Memory
90178		FiloSanza	Dreaming (IOI13_dreaming)	C++14	47 / 100	1088 ms	9080 KiB

dreaming

#pragma GCC optimize("O3")
#include "dreaming.h"
#include <bits/stdc++.h>
 
const int INF = 2e9;
 
using namespace std;
 
struct arco
{
	int to, p;
};
int N;
vector<vector<arco>> g;
vector<int> dist;
vector<pair<int, int>> centers;
vector<int> temp;
vector<int> padre;
queue<int> changed;
queue<int> q;
 
int bfs(int node, bool precalcolo){
	dist[node] = 0;
	q.push(node);
 
	int maxiNode = node;
	int maxi = 0;
	while(!q.empty()){
		auto curr = q.front();
		q.pop();
 
		if(maxi < dist[curr])
			maxi = dist[curr], maxiNode = curr;
 
		for(auto i : g[curr]){
			if(dist[i.to] > dist[curr] + i.p){
				padre[i.to] = curr;
				changed.push(i.to);
				q.push(i.to);
				dist[i.to] = dist[curr] + i.p;
			}
		}
	}
 
	// for(auto i : padre)cout << i << " ";
		// cout << "\n\n";
	if(precalcolo)
		temp.push_back(maxiNode);
	else{
		int diameter = maxi;
		int center = maxiNode;
		int curr = maxiNode;
		maxi = maxi;
		while(padre[curr] != -1){
			curr = padre[curr];
			if(max(diameter-dist[curr], dist[curr]) < maxi){
				maxi = max(diameter-dist[curr], dist[curr]);
				center = curr;
			}
		}
 
		centers.push_back({maxi, center});
	}
 
	while(!changed.empty()){
		padre[changed.front()] = -1;
		changed.pop();
	}

	return *max_element(dist.begin(), dist.end());
}
 
int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
	::N = N;
    g.resize(N);
    dist.resize(N);
	centers.reserve(N);
	temp.reserve(N);
	padre.resize(N, -1);
 
    for(int i=0; i<M; i++){
    	g[A[i]].push_back({B[i], T[i]});
    	g[B[i]].push_back({A[i], T[i]});
    }
 
	fill(dist.begin(), dist.end(), INF);
    for(int i=0; i<N; i++) if(dist[i] == INF)
    	bfs(i, true);
 
	fill(dist.begin(), dist.end(), INF);
    for(auto i : temp)
    	bfs(i, false);
 
    sort(centers.begin(), centers.end());
 
    for(int i=0; i<centers.size()-1; i++){
    	// cout << "Aggiungo gli archi " << centers[i].second << " " << centers[centers.size()-1].second << "\n";
    	g[centers[i].second].push_back({centers[centers.size()-1].second, L});
    	g[centers[centers.size()-1].second].push_back({centers[i].second, L});
    }

    fill(dist.begin(), dist.end(), INF);
   	bfs(1, true);
   	int node = max_element(dist.begin(), dist.end()) - dist.begin();
	fill(dist.begin(), dist.end(), INF);
   	return bfs(node, false);
}

Compilation message (stderr)

dreaming.cpp: In function 'int travelTime(int, int, int, int*, int*, int*)':
dreaming.cpp:87:28: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
     for(int i=0; i<N; i++) if(dist[i] == INF)
                            ^~
dreaming.cpp:90:2: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
  fill(dist.begin(), dist.end(), INF);
  ^~~~
dreaming.cpp:96:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0; i<centers.size()-1; i++){
                  ~^~~~~~~~~~~~~~~~~

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