Submission #563473

#	Time	Username	Problem	Language	Result	Execution time	Memory
563473		piOOE	Beads and wires (APIO14_beads)	C++17	28 / 100	1089 ms	5332 KiB

beads

//#define _GLIBCXX_DEBUG

//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("unroll-loops")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")

#include <bits/stdc++.h>

using namespace std;

//#include <ext/pb_ds/assoc_container.hpp>
//
//using namespace __gnu_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 normal_queue = priority_queue<T, vector<T>, greater<>>;

mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());

#define trace(x) cout << #x << ": " << (x) << endl;
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
#define uniq(x) x.resize(unique(all(x)) - begin(x))
#define sz(s) ((int) size(s))
#define pii pair<int, int>
#define mp(x, y) make_pair(x, y)
#define int128 __int128
#define pb push_back
#define popb pop_back
#define eb emplace_back
#define fi first
#define se second
#define itn int

typedef long long ll;
typedef pair<ll, ll> pll;
typedef long double ld;
typedef double db;
typedef unsigned int uint;


template<typename T>
bool ckmn(T &x, T y) {
    if (x > y) {
        x = y;
        return true;
    }
    return false;
}

template<typename T>
bool ckmx(T &x, T y) {
    if (x < y) {
        x = y;
        return true;
    }
    return false;
}

int bit(int x, int b) {
    return (x >> b) & 1;
}

int rand(int l, int r) { return (int) ((ll) rnd() % (r - l + 1)) + l; }


const ll infL = 3e18;
const int infI = 1000000000 + 7;
const int infM = 0x3f3f3f3f; //a little bigger than 1e9
const ll infML = 0x3f3f3f3f3f3f3f3fLL; //4.5e18
const int N = 200002;
const int mod = 998244353;
const ld eps = 1e-9;

vector<pair<int, int>> g[N];

ll dp[2][N];

int p[N], wp[N];

void precalc(int v, int par) {
    p[v] = par;
    for (auto [to, w]: g[v]) {
        if (to != par) {
            wp[to] = w;
            precalc(to, v);
        }
    }
}

void dfs(int v) {
    dp[0][v] = dp[1][v] = 0;
    ll nw = -infL;
    for (auto [to, w]: g[v]) {
        if (to != p[v]) {
            dfs(to);
            ll val = max(dp[1][to], dp[0][to]);
            dp[0][v] += val;
            ckmx(nw, dp[0][to] + w - val);
        }
    }
    if (p[v] != -1)
        ckmx(dp[1][v], dp[0][v] + nw + wp[v]);
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n;
    cin >> n;
    for (int i = 1; i < n; ++i) {
        int a, b, w;
        cin >> a >> b >> w;
        --a, --b;
        g[a].emplace_back(b, w);
        g[b].emplace_back(a, w);
    }
    ll ans = -infL;
    for (int i = 0; i < n; ++i) {
        precalc(i, -1);
        dfs(i);
        ckmx(ans, max(dp[1][i], dp[0][i]));
    }
    cout << ans;
    return 0;
}

• Subtask 1: 13 / 13
• Subtask 2: 15 / 15
• Subtask 3: 0 / 29
• Subtask 4: 0 / 43