Submission #695200

#	Time	Username	Problem	Language	Result	Execution time	Memory
695200		finn__	Stranded Far From Home (BOI22_island)	C++17	0 / 100	150 ms	19248 KiB

island

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

struct DSU
{
    vector<int64_t> parent, weight;
    vector<bool> is_bad;

    DSU(size_t n, vector<int64_t> const &s)
    {
        parent = vector<int64_t>(n, -1);
        weight = vector<int64_t>(s.begin(), s.end());
        is_bad = vector<bool>(n, 0);
    }

    void update_bad(int u)
    {
        if (parent[u] >= 0)
        {
            update_bad(parent[u]);
            is_bad[u] = is_bad[u] || is_bad[parent[u]];
        }
    }

    int root(int u)
    {
        if (parent[u] < 0)
            return u;
        return parent[u] = root(parent[u]);
    }

    void merge(int u, int v)
    {
        update_bad(u);
        update_bad(v);
        u = root(u), v = root(v);
        if (u == v)
            return;

        if (parent[u] > parent[v])
            swap(u, v);

        weight[u] += weight[v];
        parent[u] += parent[v];
        parent[v] = u;
    }

    void mark_bad(int u)
    {
        is_bad[root(u)] = 1;
    }

    int64_t component_weight(int u)
    {
        update_bad(u);
        return weight[root(u)];
    }

    bool get_bad(int u)
    {
        update_bad(u);
        return is_bad[u];
    }
};

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    size_t n, m;
    cin >> n >> m;

    vector<int64_t> s(n);
    for (int64_t &x : s)
        cin >> x;

    vector<pair<int64_t, unsigned>> nodes(n);
    for (size_t i = 0; i < n; i++)
        nodes[i] = {s[i], i};
    sort(nodes.begin(), nodes.end());

    vector<vector<unsigned>> g(n);
    for (size_t i = 0; i < m; i++)
    {
        unsigned u, v;
        cin >> u >> v;
        g[u - 1].push_back(v - 1);
        g[v - 1].push_back(u - 1);
    }

    DSU dsu(n, s);

    for (auto const &[x, u] : nodes)
    {
        for (unsigned const &v : g[u])
        {
            if (s[v] <= x)
            {
                if (dsu.component_weight(v) >= x)
                    dsu.merge(u, v);
            }
        }
    }

    for (int i = 0; i < n; i++)
        cout << (dsu.root(i) == dsu.root(nodes.back().second) ? 1 : 0);
    cout << '\n';
}

Compilation message (stderr)

island.cpp: In function 'int main()':
island.cpp:106:23: warning: comparison of integer expressions of different signedness: 'int' and 'size_t' {aka 'long unsigned int'} [-Wsign-compare]
  106 |     for (int i = 0; i < n; i++)
      |                     ~~^~~

• Subtask 1: 0 / 10
• Subtask 2: 0 / 10
• Subtask 3: 0 / 15
• Subtask 4: 0 / 30
• Subtask 5: 0 / 35