Submission #850476

#	Time	Username	Problem	Language	Result	Execution time	Memory
850476		MinaRagy06	Stranded Far From Home (BOI22_island)	C++17	100 / 100	625 ms	63016 KiB

island

#include <bits/stdc++.h>
using namespace std;
typedef int64_t ll;

const int N = 200'005;
int par[N], sz[N], par2[N], bad[N], a[N];
ll cnt[N];
set<array<int, 3>> adj[N];
pair<int, int> find2(int u) {
    if (par2[u] == u) {
        return {u, bad[u]};
    }
    pair<int, int> v = find2(par2[u]);
    bad[u] |= v.second;
    par2[u] = v.first;
    return {par2[u], bad[u]};
}
pair<int, int> find(int u) {
    if (par[u] == u) {
        return {u, bad[u]};
    }
    pair<int, int> v = find(par[u]);
    par[u] = v.first;
    return {par[u], bad[u]};
}
void join2(int u, int v) {
    u = find2(u).first;
    v = find2(v).first;
    if (u == v) return;
    par2[v] = u;
}
void join(int u, int v) {
    u = find(u).first, v = find(v).first;
    if (u == v) return;
    if (sz[u] < sz[v]) swap(u, v);
    par[v] = u, sz[u] += sz[v], cnt[u] += cnt[v];
    for (auto [vnxt, nxt, src] : adj[v]) {
        int x = find(nxt).first;
        if (x != u) {
            adj[u].insert({a[nxt], nxt, src});
        } else {
            adj[u].erase({a[src], src, nxt});
        }
    }
    adj[v].clear();
}
int main() {
    ios_base::sync_with_stdio(0), cin.tie(0);
    int n, m;
    cin >> n >> m;
    for (int i = 0; i < n; i++) {
        par[i] = i, par2[i] = i, sz[i] = 1, bad[i] = 0;
        cin >> cnt[i];
        a[i] = cnt[i];
    }
    for (int i = 0, u, v; i < m; i++) {
        cin >> u >> v;
        u--, v--;
        adj[u].insert({a[v], v, u});
        adj[v].insert({a[u], u, v});
    }
    priority_queue<pair<ll, pair<int, int>>> pq;
    for (int i = 0; i < n; i++) {
        pq.push({-cnt[i], {i, i}});
    }
    while (pq.size()) {
        int node = pq.top().second.first;
        int node2 = pq.top().second.second;
        ll val = -pq.top().first;
        pq.pop();
        if (node != par[node]) {
            continue;
        }
        if (val != cnt[node]) {
            continue;
        }
        if (sz[node] == n) {
            continue;
        }
        if (adj[node].empty() || val < (*adj[node].begin())[0]) {
            bad[node2] = 1;
            continue;
        }
        int x = (*adj[node].begin())[1];
        join(node, x);
        int New = find(node).first;
        join2(node2, x);
        int New2 = find2(node).first;
        pq.push({-cnt[New], {New, New2}});
    }
    for (int i = 0; i < n; i++) {
        cout << !find2(i).second;
    }
    cout << '\n';
    return 0;
}

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 15 / 15
• Subtask 4: 30 / 30
• Subtask 5: 35 / 35