Submission #590591

#	Time	Username	Problem	Language	Result	Execution time	Memory
590591		mohammad_kilani	Dreaming (IOI13_dreaming)	C++17	100 / 100	162 ms	15580 KiB

dreaming

#include "dreaming.h"
#include <bits/stdc++.h>
using namespace std;

vector< vector< pair< int , int > > > adj;

vector< int > color;

vector< int > max_distance;

vector< pair< int , int > > minPossibleMaxDistance;

int color_counter;

void DFSAndcolor(int node,int parent){
    color[node] = color_counter;
    for(int i = 0 ;i < (int)adj[node].size();i++){
        if(adj[node][i].first != parent)
            DFSAndcolor(adj[node][i].first , node);
    }
}





bool DFS(int node,int parent,int destination){
    if(node == destination)
        return true;
    for(int i = 0 ;i < (int)adj[node].size();i++){
        if(adj[node][i].first == parent)
            continue;
        if(DFS(adj[node][i].first,  node, destination))
            return true;
    }
    return false;
}

int maximum_distance , best_node;

void DFS2(int node,int parent,int distance){
    if(distance > maximum_distance){
        maximum_distance = distance;
        best_node = node;
    }
    for(int i = 0 ;i < (int)adj[node].size();i++){
        if(adj[node][i].first != parent)
            DFS2(adj[node][i].first , node , distance + adj[node][i].second);
    }
}

void DFS3(int node,int parent,int distance){
    max_distance[node] = max(max_distance[node] , distance);
    for(int i = 0 ;i < (int)adj[node].size();i++){
        if(adj[node][i].first != parent)
            DFS3(adj[node][i].first, node,  distance + adj[node][i].second);
    }
}

int FindLongestPath(){
    maximum_distance = -1;
    DFS2(0 , -1 , 0);
    maximum_distance = -1;
    DFS2(best_node , -1 , 0);
    return maximum_distance;
}

int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
    adj.resize(N);
    color.resize(N , -1);
    max_distance.resize(N , -1);
    for(int i = 0 ;i < M;i++){
        adj[A[i]].push_back(make_pair(B[i] , T[i]));
        adj[B[i]].push_back(make_pair(A[i] , T[i]));
    }

    for(int i = 0 ;i < N;i++){
        if(color[i] != -1)
            continue;
        DFSAndcolor(i , -1);
        color_counter++;
        maximum_distance = -1;
        DFS2(i , -1 , 0);
        int x = best_node;
        maximum_distance = -1;
        DFS2(x , -1 , 0);
        int y = best_node;
        DFS3(x , -1 , 0);
        DFS3(y , -1 , 0);
    }
    minPossibleMaxDistance.resize(color_counter , make_pair((int)1e9 , -1));


    for(int i = 0 ;i < N;i++){
        if(max_distance[i] < minPossibleMaxDistance[color[i]].first)
            minPossibleMaxDistance[color[i]] = make_pair(max_distance[i] , i);
        //node i is at the component with color, color[i] , has max distance with value of maximum_distance[i]
    }

    sort(minPossibleMaxDistance.begin(), minPossibleMaxDistance.end());

    for(int i = 0 ;i < (int)minPossibleMaxDistance.size() - 1;i++){
        int current_best_node = minPossibleMaxDistance[i].second;
        int node_in_the_middle = minPossibleMaxDistance.back().second;
        adj[current_best_node].push_back(make_pair(node_in_the_middle , L));
        adj[node_in_the_middle].push_back(make_pair(current_best_node , L));
    }

    return FindLongestPath();
}

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