Submission #1283875

#	Time	Username	Problem	Language	Result	Execution time	Memory
1283875		thaibeo123	Construction of Highway (JOI18_construction)	C++20	100 / 100	181 ms	18332 KiB

construction

#include <bits/stdc++.h>
using namespace std;

#define NAME "A"
#define ll long long
#define fi first
#define se second
#define pb push_back
#define all(x) x.begin(), x.end()
#define MASK(x) (1ll << (x))
#define BIT(x, i) (((x) >> (i)) & 1)

const int N = 1e5 + 5;

struct FenwickTree {
    int n;
    vector<int> fen;

    FenwickTree() {}
    FenwickTree(int n): n(n), fen(n + 1) {}

    void update(int x, int v) {
        for (int i = x; i <= n; i += i & -i) {
            fen[i] += v;
        }
    }

    int get(int x) {
        int res = 0;
        for (int i = x; i > 0; i -= i & -i) {
            res += fen[i];
        }
        return res;
    }
};

int n;
int a[N], p[N], sz[N], head[N], hi[N];
vector<int> vals, g[N];
vector<pair<int, int>> edge, s[N];
FenwickTree fen;

void dfs(int u, int par) {
    sz[u] = 1;
    p[u] = par;
    hi[u] = hi[par] + 1;
    for (int v : g[u]) {
        if (v == par) continue;
        dfs(v, u);
        sz[u] += sz[v];
    }
}

void hld(int u, int par, int he) {
    head[u] = he;
    int beo = 0;
    for (int v : g[u]) {
        if (v == par) continue;
        if (sz[v] > sz[beo]) {
            beo = v;
        }
    }
    if (beo) {
        hld(beo, u, he);
    }
    for (int v : g[u]) {
        if (v != par && v != beo) {
            hld(v, u, v);
        }
    }
}

void update(int u, int val) {
    while (u) {
        int h = head[u];
        int d = hi[u] - hi[head[u]] + 1;
        while (s[h].size() && s[h].back().fi <= d) {
            s[h].pop_back();
        }
        s[h].pb({d, val});
        u = p[h];
    }
}

ll get(int u) {
    ll ans = 0;
    vector<pair<int, int>> vec;
    while (u) {
        int h = head[u];
        int d = hi[u] - hi[head[u]] + 1;
        int last = 0;
        vector<pair<int, int>> cur;
        for (int i = s[h].size() - 1; i >= 0; i--) {
            int x = s[h][i].fi, val = s[h][i].se;
            cur.pb({min(x, d) - last, val});
            last = x;
            if (x >= d) break;
        }
        for (int i = cur.size() - 1; i >= 0; i--) {
            vec.pb(cur[i]);
        }
        u = p[h];
    }
    for (auto it : vec) {
        ans += 1ll * it.fi * fen.get(it.se - 1);
        fen.update(it.se, it.fi);
    }
    for (auto it : vec) {
         fen.update(it.se, -it.fi);
    }
    return ans;
}

void input() {
    cin >> n;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
        vals.pb(a[i]);
    }
    sort(all(vals));
    vals.erase(unique(all(vals)), vals.end());
    for (int i = 1; i <= n; i++) {
        a[i] = upper_bound(all(vals), a[i]) - vals.begin();
    }
    fen = FenwickTree(vals.size());

    for (int i = 1; i < n; i++) {
        int u, v;
        cin >> u >> v;
        g[u].pb(v);
        g[v].pb(u);
        edge.pb({u, v});
    }
}

void solve() {
    dfs(1, 0);
    hld(1, 0, 1);
    for (auto it : edge) {
        int u = it.fi, v = it.se;
        cout << get(u) << "\n";
        update(v, a[v]);
    }
}

signed main() {
    if (fopen(NAME".INP", "r")) {
        freopen(NAME".INP", "r", stdin);
        freopen(NAME".OUT", "w", stdout);
    }
    cin.tie(0)->sync_with_stdio(0);

    input();
    solve();

    return 0;
}

Compilation message (stderr)

construction.cpp: In function 'int main()':
construction.cpp:148:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  148 |         freopen(NAME".INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
construction.cpp:149:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  149 |         freopen(NAME".OUT", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 7 / 7
• Subtask 2: 9 / 9
• Subtask 3: 84 / 84