Submission #882854

#	Time	Username	Problem	Language	Result	Execution time	Memory
882854		nikd	Dreaming (IOI13_dreaming)	C++17	18 / 100	41 ms	14420 KiB

dreaming

#include <bits/stdc++.h>
#include "dreaming.h"
#define MAXN 100001
using namespace std;

int f;
int max_dis;
int par[MAXN];
int cont=0;
vector<int> mintree;
bool vis[MAXN];
vector<pair<int, int>> adj[MAXN];
int dist[MAXN]={};

void dfs1(int v, int p){
    /*vis[v]=true;
    for(auto u: adj[v]){
        if(u.first!=p){
            dist[u.first]=dist[v]+u.second;
            if(dist[u.first]>max_dis){
                max_dis=dist[u.first];
                f=u.first;
            }
            dfs1(u.first, v);
        }
    }*/
    vis[v] = 1;
    if(dist[v] > max_dis)
    {
        f = v;
        max_dis = dist[v];
    }

     // applying the standard dfs 
    for( auto u: adj[v] )
    {
        if(u.first!=p)
        {
            dist[u.first]=dist[v]+u.second;
            dfs1(u.first, v) ;
        }
    }
}

void dfs2(int v, int p){
    /*vis[v]=true;
    for(auto u: adj[v]){
        if(u.first!=p){
            dist[u.first]=dist[v]+u.second;
            if(dist[u.first]>max_dis){
                max_dis=dist[u.first];
                f=u.first;
            }
            dfs1(u.first, v);
        }
    }*/
    if(dist[v] > max_dis)
    {
        f = v;
        max_dis = dist[v];
    }

     // applying the standard dfs 
    for( auto u: adj[v] )
    {
        if(u.first!=p)
        {
            dist[u.first]=dist[v]+u.second;
            par[u.first]=v;
            dfs2(u.first, v) ;
        }
    }
}

/*void dfs2(int v, int p){
    par[v]=p;
    for(auto u: adj[v]){
        if(u.first!=p){
            dist[u.first]=dist[v]+u.second;
            if(dist[u.first]>max_dis){
                max_dis=dist[u.first];
                f=u.first;
            }
            dfs2(u.first, v);
        }
    }
}*/

int travelTime(int N, int M, int L, int A[], int B[], int T[]){
    for(int i = 0; i<M; i++){
        adj[A[i]].push_back({B[i], T[i]});
        adj[B[i]].push_back({A[i], T[i]});
    }
    for(int i = 0; i<N; i++) vis[i]=false;
    for(int i = 0; i<N; i++){
        if(!vis[i]){
            mintree.push_back(INT_MAX);
            max_dis=INT_MIN;
            f=-1;
            dist[i]=0;
            dfs1(i, i);
            int a = f;
            dist[a]=0;
            max_dis=INT_MIN;
            f =-1;
            dfs2(a, a);
            int b = f;
            int d= max_dis/2;
            int last=-1;
            while(dist[b]>d){
                last=b;
                b=par[b];
            }
            if(last==-1){
                mintree[cont]=dist[b];
            }
            else{
                mintree[cont]=min(dist[last], max_dis-dist[b]);
            }
            cont++;
        }
    }
    sort(mintree.begin(), mintree.end());
    int sol;
    int n = cont;
    
    if(n==2){
        sol = mintree[0]+mintree[1]+L;
    }
    else if(n==1) sol =mintree[0];
    else{
        sol=max(mintree[n-1]+mintree[n-2]+L, mintree[n-2]+mintree[n-3]+2*L);
    }
    
    return sol;
}

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