Submission #1319262

#	Time	Username	Problem	Language	Result	Execution time	Memory
1319262		darkdevilvaqif	Dreaming (IOI13_dreaming)	C++20	100 / 100	102 ms	12864 KiB

dreaming

/*
  _      __        __         __        ____                    ___    _                   __
 | | /| / / ___ _ / /_ ____  / /       / __ \  ___  ___        / _ \  (_) ___  ____ ___   / /
 | |/ |/ / / _ `// __// __/ / _ \     / /_/ / / _ \/ -_)      / ___/ / / / -_)/ __// -_) /_/ 
 |__/|__/  \_,_/ \__/ \__/ /_//_/     \____/ /_//_/\__/      /_/    /_/  \__/ \__/ \__/ (_)  
                                                                                             
*/

#pragma GCC optimize("O3")
#pragma GCC optimize ("unroll-loops")
// #pragma GCC target("avx2")
#include "dreaming.h"
#include <bits/stdc++.h>
using namespace std;
 
// constants

// functions
int GCD(int A, int B);
int LCM(int A, int B);
int power(int base, int exponent);

// structs
struct graph
{
    vector <vector <pair <int, int> > > g;
    vector <int> dist, par;
    vector <bool> used;
    
    void cleanse()
    {
        fill(dist.begin(), dist.end(), 0);
        fill(par.begin(), par.end(), -1);
        fill(used.begin(), used.end(), false);
    }
    
    void prep(int n)
    {
        g.resize(n);
        dist.resize(n);
        par.resize(n);
        used.resize(n);
        
        cleanse();
    }
    
    void adde(int u, int v, int w)
    {
        g[u].push_back({v, w});
        g[v].push_back({u, w});
    }
    
    vector <int> path;
    void DFS(int v)
    {
        used[v] = true;
        path.push_back(v);
        
        for (auto [u, w] : g[v])
        {
            if (used[u])
            {
                continue;
            }
            
            par[u] = v;
            dist[u] = dist[v] + w;
            DFS(u);
        }
    }
};

// globals

// variables

// iterators
int i;

// notes
/*
My favorite anime is One Piece(obviously)
My oshi(Yes, I have an oshi, deal with it) is Kamil_Tsubaki

 -stuff you should look for-
* int overflow, array bounds
* special cases (n=1?)
* do something instead of nothing and stay organized
* WRITE STUFF DOWN
* DON'T GET STUCK ON ONE APPROACH

continue - skip the rest in the loop
*/
 
int travelTime(int N, int M, int L, int A[], int B[], int T[])
{
    graph G;
    G.prep(N);
    for (i = 0; i < M; i++)
    {
        G.adde(A[i], B[i], T[i]);
    }
    
    vector <int> radis;
    int ans = 0;
    for (i = 0; i < N; i++)
    {
        if (G.used[i])
        {
            continue;
        }
        
        G.path.clear();
        G.DFS(i);
        int mx = 0, u = i;
        for (auto v : G.path)
        {
            G.used[v] = false;
            if (mx < G.dist[v])
            {
                mx = G.dist[v];
                u = v;
            }
            G.dist[v] = 0;
            G.par[v] = -1;
        }
        G.path.clear();
        G.DFS(u);
        mx = 0;
        for (auto v : G.path)
        {
            if (mx < G.dist[v])
            {
                mx = G.dist[v];
                u = v;
            }
        }
        ans = max(ans, mx);
        
        int R = mx, cur = u;
        while (cur != -1)
        {
            int dist1 = G.dist[cur], dist2 = mx - G.dist[cur];
            R = min(R, max(dist1, dist2));
            cur = G.par[cur];
        }
        radis.push_back(R);
    }
    
    sort(radis.begin(), radis.end(), greater<int>());
    if ((int)radis.size() >= 2)
    {
        ans = max(ans, radis[0] + radis[1] + L);
    }
    if ((int)radis.size() >= 3)
    {
        ans = max(ans, radis[1] + radis[2] + 2 * L);
    }
    
    return ans;
}
 
int GCD(int A, int B)
{
    if (!A)
    {
        return B;
    }
    return GCD(B % A, A);
}

int LCM(int A, int B)
{
    return A * B / GCD(A, B);
}

int power(int base, int exponent)
{
    int res = 1;
    while (exponent) 
    {
        if (exponent & 1)
        { 
            res *= base;
        }
        base *= base;
        exponent >>= 1;    
    }
    return res;
}

/*
$$$$$$$$\ $$$$$$$$\ 
$$  _____|\____$$  |
$$ |          $$  / 
$$$$$\       $$  /  
$$  __|     $$  /   
$$ |       $$  /    
$$$$$$$$\ $$$$$$$$\ 
\________|\________|
*/

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