Submission #1283706

#	Time	Username	Problem	Language	Result	Execution time	Memory
1283706		thaibeo123	Construction of Highway (JOI18_construction)	C++20	16 / 100	2095 ms	2728 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 = 2e5 + 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;
    }
};
FenwickTree fen;

int n;
int c[N], a[N], p[N];
vector<int> vals;

int getans(int u) {
    int ans = 0;
    while (u != 0) {
        ans += fen.get(a[u] - 1);
        //cout << u << " " << a[u] << " " << fen.get(a[u]) << "\n";
        fen.update(a[u], 1);
        u = p[u];
    }
    return ans;
}

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

void solve() {
    fen = FenwickTree(vals.size());
    for (int i = 1; i < n; i++) {
        int u, v;
        cin >> u >> v;
        p[v] = u;
        int ans = getans(u);
        while (u != 0) {
            fen.update(a[u], -1);
            u = p[u];
        }
        int cost = c[v];
        while (v != 0) {
            a[v] = cost;
            v = p[v];
        } 
        cout << ans << "\n";
    }
}

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

    int t = 1;
    //cin >> t;
    while (t--) {
        input();
        solve();
    }

    return 0;
}

Compilation message (stderr)

construction.cpp: In function 'int main()':
construction.cpp:89:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   89 |         freopen(NAME".INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
construction.cpp:90:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   90 |         freopen(NAME".OUT", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 7 / 7
• Subtask 2: 9 / 9
• Subtask 3: 0 / 84