Submission #1023254

#	Time	Username	Problem	Language	Result	Execution time	Memory
1023254		vjudge1	Dreaming (IOI13_dreaming)	C++17	100 / 100	61 ms	43440 KiB

dreaming

#ifndef LOCAL
#pragma GCC optimize("Ofast,unroll-loops,inline")
// Bitwise pragma fuck
// #pragma GCC target("avx,avx2,bmi")
 
// Judges with GCC >= 12 only needs Ofast
// #pragma GCC optimize("O3,no-stack-protector,fast-math,unroll-loops,tree-vectorize")
// MLE optimization
// #pragma GCC optimize("conserve-stack")
// Old judges
// #pragma GCC target("sse4.2,popcnt,lzcnt,abm,mmx,fma,bmi,bmi2")
// New judges. Test with assert(__builtin_cpu_supports("avx2"));
// #pragma GCC target("arch=skylake")
// Atcoder
// #pragma GCC target("avx2,popcnt,lzcnt,abm,bmi,bmi2,fma")
#endif
 
#ifndef LOCAL
#include "dreaming.h"
#endif
#include <bits/stdc++.h>
using namespace std;
 
// Wish you can debug? YesYes
#ifndef LOCAL
#define cerr \
    if (0)   \
    cerr
#endif
 
// Policy based DS?
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// using namespace __gnu_pbds;
 
// Who tf deal with overflow
// #define int long long
 
/*
pbds blog :
https://codeforces.com/blog/entry/11080
https://codeforces.com/blog/entry/13279
*/
// Useful pbds
// template <typename T>
// using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
// template <typename T>
// using ordered_multiset = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>;
// typedef trie<string, null_type, trie_string_access_traits<>, pat_trie_tag, trie_prefix_search_node_update> pref_trie;
 
#define el '\n'
#define mpp make_pair
#define pb push_back
#define ppb pop_back
#define pf push_front
#define emp emplace_back
#define fi first
#define nd second
#define forinc(i, a, b) for (int i = (a); i <= (b); i++)
#define fordec(i, a, b) for (int i = (a); i >= (b); i--)
#define alle(x) (x).begin(), (x).end()
#define ralle(x) (x).rbegin(), (x).rend()
#define mms(a, v) memset(a, v, sizeof(a))
#define lwb(a, v) lower_bound((a).begin(), (a).end(), v)
#define upb(a, v) upper_bound((a).begin(), (a).end(), v)
#define bit(i, a) (((a) >> (i)) & 1)
 
#define BIT_SET(a, b) ((a) |= (1ULL << (b)))
#define BIT_CLEAR(a, b) ((a) &= ~(1ULL << (b)))
#define BIT_FLIP(a, b) ((a) ^= (1ULL << (b)))
#define BIT_CHECK(a, b) (!!((a) & (1ULL << (b))))
#define BITMASK_SET(x, mask) ((x) |= (mask))
#define BITMASK_CLEAR(x, mask) ((x) &= (~(mask)))
#define BITMASK_FLIP(x, mask) ((x) ^= (mask))
#define BITMASK_CHECK_ALL(x, mask) (!(~(x) & (mask)))
#define BITMASK_CHECK_ANY(x, mask) ((x) & (mask))
#define POPCNT(mask) __builtin_popcount(mask)
#define POPCNTLL(mask) __builtin_popcountll(mask)
#define CTZ(mask) __builtin_ctz(mask)
#define CTZLL(mask) __builtin_ctzll(mask)
 
typedef long long ll;
typedef unsigned long long ull;
typedef long double ldb;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef map<int, int> mii;
typedef map<ll, ll> mll;
typedef vector<bool> vb;
 
template <typename T, typename U>
inline void maximize(T &x, U y)
{
    if (y < x)
        x = y;
}
template <typename T, typename U>
inline void minimize(T &x, U y)
{
    if (x < y)
        x = y;
}
inline int add_m(int a, int b, int mod)
{
    int res = a + b;
    return (res >= mod ? res - mod : res);
}
inline int mod_neg(int a, int b, int mod)
{
    int res;
    if (abs(a - b) < mod)
        res = a - b;
    else
        res = (a - b) % mod;
    return (res < 0 ? res + mod : res);
}
inline int mul_wmod(int a, int b, int c)
{
    ll res = (ll)a * b;
    return (res >= c ? res % c : res);
}
inline int mul_wnmod(int a, int b, int c)
{
    ll res = (ll)a * b;
    return ((res % c) + c) % c;
}
 
// Debugger Utils
template <typename A, typename B>
ostream &operator<<(ostream &os, const pair<A, B> &p) { return os << '(' << p.first << ", " << p.second << ')'; }
 
template <size_t i, class T>
ostream &print_tuple_utils(ostream &out, const T &tup)
{
    if constexpr (i == tuple_size<T>::value)
        return out << ")";
    else
        return print_tuple_utils<i + 1, T>(out << (i ? ", " : "(") << get<i>(tup), tup);
}
template <class... U>
ostream &operator<<(ostream &out, const tuple<U...> &t)
{
    return print_tuple_utils<0, tuple<U...>>(out, t);
}
#define db(val) "[" #val " = " << (val) << "] "
// End if debugger utils
 
namespace Hasher
{
    struct custom_hash
    {
        static uint32_t splitmix64(uint32_t x)
        {
            x += 0x9e3779b97f4a7c15;
            x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
            x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
            return x ^ (x >> 31);
        }
        size_t operator()(uint64_t x) const
        {
            static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
            return splitmix64(x + FIXED_RANDOM);
        }
    };
    struct hash_pair
    {
        template <class T1, class T2>
        size_t operator()(const pair<T1, T2> &p) const
        {
            auto hash1 = custom_hash{}(p.first);
            auto hash2 = custom_hash{}(p.second);
            if (hash1 != hash2)
                return hash1 ^ hash2;
            return hash1;
        }
    };
    struct hash_pair_pair
    {
        template <class T1, class T2>
        size_t operator()(const pair<T1, T2> &p) const
        {
            auto hash1 = custom_hash{}(p.first);
            auto hash2 = hash_pair{}(p.second);
            if (hash1 != hash2)
                return hash1 ^ hash2;
            return hash1;
        }
    };
}
using namespace Hasher;
 
const string taskname = "";
const bool tc = false;
 
const int oo = 1e9, mod = 1e9 + 7;
const int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
const ll ool = 1e18;
const ldb eps = 1e-6;
const int MAXN = 1e6;
 
/*
Author: normankr07
Problem:
    - IOI 2013 - Dreaming
Submission links:
    - https://oj.uz/problem/view/IOI13_dreaming
Editorial links:
    - https://www.quora.com/What-is-the-solution-for-Dreaming-on-IOI-2013
    - http://blog.brucemerry.org.za/2013/07/ioi-2013-day-1-analysis.html
    - http://math.fau.edu/locke/Center.htm
Algorithm:
    - Find the center with maxmimum eccentricity, connect all of the center with that center
 
*/
 
vector<pii> adj[MAXN];
bool vis[MAXN];
pii max1[MAXN];
int max2[MAXN], dep[MAXN];
void DFS_maxcen(int u, int p)
{
    vis[u] = 1;
    max1[u] = {0, u};
    for (auto &[v, w] : adj[u])
    {
        if (v == p)
            continue;
        DFS_maxcen(v, u);
        max1[u] = max(max1[u], {max1[v].fi + w, max1[v].nd});
    }
}
 
int reDFS(int u, int p)
{
    max2[u] = max(max2[u], dep[u]);
    int ans = max2[u];
    for (auto &[v, w] : adj[u])
    {
        if (v == p)
            continue;
        dep[v] = dep[u] + w;
        ans = min(ans, reDFS(v, u));
    }
    return ans;
}
 
int travelTime(int N, int M, int L, int A[], int B[], int T[])
{
    for (int i = 0; i < M; i++)
    {
        adj[A[i]].pb({B[i], T[i]});
        adj[B[i]].pb({A[i], T[i]});
    }
    int ans = 0;
    vi dia;
    forinc(i, 0, N - 1)
    {
        if (vis[i])
            continue;
        DFS_maxcen(i, i);
        // Center with max ecc of subtree r[i];
        int x = max1[i].second;
        cerr << "Current root: " << i << el;
        cerr << db(max1[i]) << el;
        DFS_maxcen(x, x);
        // Check root x;
        int y = max1[x].second;
        cerr << db(max1[x]) << el;
        cerr << db(x) << db(y) << el;
        ans = max(ans, max1[x].first);
        dep[x] = 0;
        reDFS(x, x);
        dep[y] = 0;
        int die = reDFS(y, y);
        cerr << db(dep[x]) << db(dep[y]) << el;
        dia.pb(die);
    }
    sort(ralle(dia));
    if (dia.size() >= 2)
        ans = max(dia[0] + dia[1] + L, ans);
    if (dia.size() >= 3)
        ans = max(dia[1] + dia[2] + L * 2, ans);
    return ans;
}
 
#ifdef LOCAL
#define MAX_N 100000
 
static int A[MAX_N];
static int B[MAX_N];
static int T[MAX_N];
 
void solve()
{
    int N, M, L, i;
    int res;
    cin >> N >> M >> L;
    for (i = 0; i < M; i++)
        cin >> A[i] >> B[i] >> T[i];
    int answer = travelTime(N, M, L, A, B, T);
    cout << answer;
}
 
int32_t main()
{
    if (fopen((taskname + ".inp").c_str(), "r"))
    {
        freopen((taskname + ".inp").c_str(), "r", stdin);
        freopen((taskname + ".out").c_str(), "w", stdout);
    }
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    int tsc = 1;
    if (tc)
    {
        cin >> tsc;
    }
    while (tsc--)
    {
        solve();
        cout << el;
    }
 
    cerr << "\n"
         << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
}
#endif
#undef int

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