Submission #1022009

#	Time	Username	Problem	Language	Result	Execution time	Memory
1022009		amine_aroua	Dreaming (IOI13_dreaming)	C++17	47 / 100	823 ms	65536 KiB

dreaming

#include "dreaming.h"
#include<bits/stdc++.h>
using namespace std;
vector<vector<pair<int ,int>>> adj;

vector<int> center;
vector<bool> vis;
int mx = 0;
int y = 0;
int z = 0;
void dfs1(int x , int p = -1 , int d = 0)
{
    vis[x] = 1;
    if(mx <= d)
    {
        mx = d;
        y = x;
    }
    for(auto [u , c] : adj[x])
    {
        if(u == p)
            continue;
        dfs1(u , x , d + c);
    }
}
vector<pair<int ,int>> par;
void dfs2(int x , int p = -1 , int d = 0)
{
    if(mx <= d)
    {
        mx = d;
        z = x;
    }
    for(auto [u , c] : adj[x])
    {
        if(u == p)
            continue;
        par[u]= {x , c};
        dfs2(u , x , d + c);
    }
}
int travelTime(int N, int M, int L, int A[], int B[], int T[])
{
    adj.assign(N , {});
    vis.assign(N , 0);
    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]});
    }
    par.assign(N , {-1 , -1});
    for(int i = 0 ; i < N ; i++)
    {
        if(!vis[i])
        {
            y = 0;
            mx = 0;
            dfs1(i);
            mx = 0;
            z = 0;
            dfs2(y);
            int sm = 0;
            int mid = z;
            int mn = mx;
            while(par[z].first != -1)
            {
                sm += par[z].second;
                if(abs(mx - 2*sm) <= mn)
                {
                    mid = par[z].first;
                    mn = abs(mx - 2*sm);
                }
                z = par[z].first;
            }
            center.push_back(mid);
        }
    }
    int ans = 0;
    for(int i = 0 ; i < (int)center.size() ; i++)
    {
        auto oadj = adj;
        for(int j = 0 ; j < (int)center.size() ; j++)
        {
            if(i == j)
                continue;
            adj[center[i]].push_back({center[j] ,L});
            adj[center[j]].push_back({center[i] , L});
        }
        y = 0;
        mx = 0;
        vis.assign(N , 0);
        dfs1(0);
        mx = 0;
        z = 0;
        dfs2(y);
        ans = max(ans , mx);
        adj = oadj;
    }
    return ans;
}

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