Submission #497968

#	Time	Username	Problem	Language	Result	Execution time	Memory
497968		abc864197532	Janjetina (COCI21_janjetina)	C++17	110 / 110	441 ms	22224 KiB

Main

#include <bits/stdc++.h>
using namespace std;
#define lli long long int
#define mp make_pair
#define pb push_back
#define eb emplace_back
#define pii pair <int, int>
#define X first
#define Y second
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
void abc() {cout << endl;}
template <typename T, typename ...U> void abc(T a, U ...b) {
    cout << a << ' ', abc(b...);
}
template <typename T> void printv(T l, T r) {
    while (l != r) cout << *l << " \n"[++l == r];
}
template <typename A, typename B> istream& operator >> (istream& o, pair<A, B> &a) {
    return o >> a.X >> a.Y;
}
template <typename A, typename B> ostream& operator << (ostream& o, pair<A, B> a) {
    return o << '(' << a.X << ", " << a.Y << ')';
}
template <typename T> ostream& operator << (ostream& o, vector<T> a) {
    if (a.empty())
        return o << "{}";
    bool is = false;
    for (T i : a) {o << (is ? ' ' : '{'), is = true, o << i;}
    return o << '}';
}
template <typename T> struct vv : vector <vector <T>> {
    vv(int n, int m, T v) : vector <vector <T>> (n, vector <T>(m, v)) {}
    vv() {}
};
template <typename T> struct vvv : vector <vv <T>> {
    vvv(int n, int m, int k, T v) : vector <vv <T>> (n, vv <T>(m, k, v)) {}
    vvv() {}
};
#ifdef Doludu
#define test(args...) abc("[" + string(#args) + "]", args)
#define owo freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout)
#else
#define test(args...) void(0)
#define owo ios::sync_with_stdio(false); cin.tie(0)
#endif
const int mod = 1e9 + 7, N = 100010, logN = 17, K = 350, M = N * 40;

int k;
vector <pii> adj[N];
int sz[N];
bool vis[N];

void dfssz(int v, int pa) {
    sz[v] = 1;
    for (auto [u, w] : adj[v]) if (u != pa && !vis[u]) {
        dfssz(u, v);
        sz[v] += sz[u];
    }
}

int dfscen(int v, int pa, int n) {
    for (auto [u, w] : adj[v]) if (u != pa && !vis[u] && sz[u] * 2 > n)
        return dfscen(u, v, n);
    return v;
}

struct BIT {
    int val[N];
    vector <int> move;
    BIT () {
        fill(val, val + N, 0);
    }
    void add(int p, int v) {
        p += 3;
        for (int i = p; i < N; i += i & (-i))
            val[i] += v, move.pb(i);
    }
    int query(int p) {
        p += 3;
        int ans = 0;
        for (int i = p; i > 0; i -= i & (-i))
            ans += val[i];
        return ans;
    }
    void reset() {
        for (int i : move)
            val[i] = 0;
        move.clear();
    }
} bit;

lli ans;
// max(mx[a], mx[b]) - dp[a] >= k + dp[b]
// mx[a] > mx[b] -> mx[a] - dp[a] >= k + dp[b]
// k + dep[b] <= mx[a] - dep[a]

vector <int> all, cc;
int mx[N], dep[N];

lli calc() {
    sort(all(cc), [&](int i, int j) {
        return mx[i] < mx[j];
    });
    lli cur = 0;
    for (int i : cc) {
        cur += bit.query(mx[i] - dep[i]);
        bit.add(k + dep[i], 1);
    }
    bit.reset();
    return cur;
}

void dfsans(int v, int pa) {
    if (~pa)
        cc.pb(v);
    else
        mx[v] = dep[v] = 0;
    for (auto [u, w] : adj[v]) if (u != pa && !vis[u]) {
        mx[u] = max(mx[v], w);
        dep[u] = dep[v] + 1;
        if (mx[u] - dep[u] >= k)
            ans++;
        dfsans(u, v);
        if (pa == -1) {
            ans -= calc();
            for (int i : cc)
                all.pb(i);
            cc.clear();
        }
    }
    if (pa == -1) {
        swap(all, cc);
        ans += calc();
        cc.clear();
    }
}

void dfscd(int v, int pa) {
    dfssz(v, pa);
    int c = dfscen(v, pa, sz[v]);
    vis[c] = true;
    dfsans(c, -1);
    for (auto [u, w] : adj[c]) if (!vis[u])
        dfscd(u, c);
}

int main () {
    owo;
    int n;
    cin >> n >> k;
    for (int i = 0, u, v, w; i < n - 1; ++i) {
        cin >> u >> v >> w, --u, --v;
        adj[u].eb(v, w), adj[v].eb(u, w);
    }
    dfscd(0, -1);
    cout << ans * 2 << endl;
}

• Subtask 1: 15 / 15
• Subtask 2: 35 / 35
• Subtask 3: 60 / 60