Submission #1083993

#	Time	Username	Problem	Language	Result	Execution time	Memory
1083993		Tymond	Dreaming (IOI13_dreaming)	C++17	100 / 100	81 ms	29196 KiB

dreaming

#include <bits/stdc++.h>
#include "dreaming.h"
using namespace std;
using ll = long long;
using ld = long double;
#define fi first
#define se second
#define vi vector<int>
#define vll vector<long long>
#define pii pair<int, int>
#define pll pair<long long, long long>
#define pb push_back
#define mp make_pair
#define eb emplace_back
#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
mt19937_64 rng64(chrono::steady_clock::now().time_since_epoch().count());
inline int rand(int l,int r){return uniform_int_distribution<int>(l, r)(rng);}
inline ll rand(ll l,ll r){return uniform_int_distribution<ll>(l, r)(rng64);}
#ifdef DEBUG
auto&operator<<(auto&o,pair<auto,auto>p){return o<<"("<<p.first<<", "<<p.second<<")";}
auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{";int i=0;for(auto e:x)o<<","+!i++<<e;return o<<"}";}
#define debug(X...)cerr<<"["#X"]: ",[](auto...$){((cerr<<$<<"; "),...)<<endl;}(X)
#else
#define debug(...){}
#endif

struct custom_hash {
    static uint64_t splitmix64(uint64_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);
    }
};

const int MAXN = 1e5 + 7;
vector<pii> g[MAXN];
int root[MAXN];
int parent[MAXN];
int mx[MAXN];
int best[MAXN];
int vis[MAXN];
int n, m, l;
int ans = 0;

void dfs(int v, int p){
    root[v] = root[p];
    parent[v] = p;
    vis[v] = 1;
    vi vec;
    for(auto [u, c] : g[v]){
        if(u == p){
            continue;
        }
        dfs(u, v);
        mx[v] = max(mx[v], mx[u] + c);
        vec.pb(mx[u] + c);
    }
    if(sz(vec) <= 1){
        return;
    }
    sort(all(vec));
    reverse(all(vec));
    ans = max(ans, vec[0] + vec[1]);
}

void dfs2(int v, int p, int k){
    vi vec;
    for(auto [u, c] : g[v]){
        if(u != p){
            vec.pb(mx[u] + c);
        }
    }

    sort(all(vec));
    reverse(all(vec));

    for(auto [u, c] : g[v]){
        if(u == p){
            continue;
        }
        int g = k + c;
        best[u] = max(mx[u], k + c);
        if(mx[u] + c == vec[0]){
            if(sz(vec) > 1){
                best[u] = max(best[u], vec[1] + c);
                g = max(g, vec[1] + c);
            }
        }else{
            best[u] = max(best[u], vec[0] + c);
            g = max(g, vec[0] + c);
        }

        dfs2(u, v, g);
    }
}

int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
    n = N;
    m = M;
    l = L;
    for(int i = 0; i < m; i++){
        g[A[i]].pb({B[i], T[i]});
        g[B[i]].pb({A[i], T[i]});
    }

    for(int i = 0; i < n; i++){
        if(!vis[i]){
            root[i] = i;
            dfs(i, i);
            best[i] = mx[i];
            dfs2(i, i, 0);
        }
    }

    pii naj = {1e9, 0};
    for(int i = 0; i < n; i++){
        if(naj.fi > best[i]){
            naj.fi = best[i];
            naj.se = i;
        }
    }

    map<int, int> mn;
    for(int i = 0; i < n; i++){
        mn[i] = 1e9;
    }

    for(int i = 0; i < n; i++){
        mn[root[i]] = min(mn[root[i]], best[i]);
    }

    if(m == n - 1){
        return ans;
    }

    if(m == n - 2){
        int sec = 0;
        for(auto ele : mn){
            if(root[ele.fi] == ele.fi && ele.fi != root[naj.se]){
                sec = ele.se;
            }
        }

        ans = max(ans, sec + naj.fi + l);
        return ans;
    }

    vi ok;
    for(auto ele : mn){
        if(root[ele.fi] == ele.fi){
            ok.pb(ele.se);
        }
    }

    sort(all(ok));
    reverse(all(ok));

    ans = max(ans, l + ok[0] + ok[1]);
    ans = max(ans, 2 * l + ok[1] + ok[2]);
    return ans;
}

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