Submission #944941

#	Time	Username	Problem	Language	Result	Execution time	Memory
944941		thinknoexit	Transport (COCI19_transport)	C++17	130 / 130	313 ms	18636 KiB

Main

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int N = 100100;
vector<pair<int, int>> adj[N];
ll ans = 0;
bool vis[N];
int sz[N], m;
ll now[N], fw[N], a[N];
vector<ll> f, c;
int dfs_sz(int v, int p = -1) {
    sz[v] = 1;
    for (auto& [x, w] : adj[v]) {
        if (x == p || vis[x]) continue;
        sz[v] += dfs_sz(x, v);
    }
    return sz[v];
}
int centroid(int v, int p, int s) {
    for (auto& [x, w] : adj[v]) {
        if (x == p || vis[x]) continue;
        if (sz[x] > s) return centroid(x, v, s);
    }
    return v;
}
void init(int v, int p, ll sum, ll d) {
    if (d >= 0) ans++;
    f.push_back(-d);
    sum += a[v];
    for (auto& [x, w] : adj[v]) {
        if (x == p || vis[x]) continue;
        init(x, v, sum - w, min(d, sum - w));
    }
}
void add(int v, int p, ll sum, ll d) {
    int idx = upper_bound(c.begin(), c.end(), -d) - c.begin();
    for (int i = idx;i <= m;i += i & -i) fw[i]++;
    sum += a[v];
    for (auto& [x, w] : adj[v]) {
        if (x == p || vis[x]) continue;
        int W = a[v] - w;
        add(x, v, sum - w, min(d, sum - w));
    }
}
void rem(int v, int p, ll sum, ll d) {
    int idx = upper_bound(c.begin(), c.end(), -d) - c.begin();
    for (int i = idx;i <= m;i += i & -i) fw[i]--;
    sum += a[v];
    for (auto& [x, w] : adj[v]) {
        if (x == p || vis[x]) continue;
        rem(x, v, sum - w, min(d, sum - w));
    }
}
void cal(int v, int p, ll sum, ll mn) {
    if (mn >= 0) {
        int idx = upper_bound(c.begin(), c.end(), sum) - c.begin();
        for (int i = idx;i > 0;i -= i & -i) ans += fw[i];
    }
    for (auto& [x, w] : adj[v]) {
        if (x == p || vis[x]) continue;
        ll W = a[x] - w;
        cal(x, v, sum + W, min(mn + W, W));
    }
}
void decom(int v) {
    v = centroid(v, v, dfs_sz(v) / 2);
    vis[v] = 1;
    init(v, v, 0, 0);
    ans--;
    // compress
    sort(f.begin(), f.end());
    for (auto& x : f) {
        if (c.empty() || x != c.back()) c.push_back(x);
    }
    m = c.size();
    add(v, v, 0, 0);
    for (auto& [x, w] : adj[v]) {
        if (vis[x]) continue;
        rem(x, v, a[v] - w, min(0ll, a[v] - w));
        cal(x, v, a[x] - w, min(0ll, a[x] - w));
        add(x, v, a[v] - w, min(0ll, a[v] - w));
    }
    rem(v, v, 0, 0);
    f.clear();
    c.clear();
    for (auto& [x, w] : adj[v]) {
        if (!vis[x]) decom(x);
    }
}
int main() {
    cin.tie(nullptr)->sync_with_stdio(false);
    int n;
    cin >> n;
    for (int i = 1;i <= n;i++) cin >> a[i];
    for (int i = 1;i < n;i++) {
        int u, v, w;
        cin >> u >> v >> w;
        adj[u].push_back({ v, w });
        adj[v].push_back({ u, w });
    }
    decom(1);
    cout << ans;
    return 0;
}

Compilation message (stderr)

transport.cpp: In function 'void add(int, int, ll, ll)':
transport.cpp:41:13: warning: unused variable 'W' [-Wunused-variable]
   41 |         int W = a[v] - w;
      |             ^

• Subtask 1: 13 / 13
• Subtask 2: 13 / 13
• Subtask 3: 13 / 13
• Subtask 4: 13 / 13
• Subtask 5: 13 / 13
• Subtask 6: 13 / 13
• Subtask 7: 13 / 13
• Subtask 8: 13 / 13
• Subtask 9: 13 / 13
• Subtask 10: 13 / 13