Submission #701611

#	Time	Username	Problem	Language	Result	Execution time	Memory
701611		Johann	Stranded Far From Home (BOI22_island)	C++14	100 / 100	222 ms	43276 KiB

island

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

#define ll long long
#define pii pair<int, int>
#define vb vector<bool>
#define vi vector<ll>
#define vpii vector<pii>
#define vvpii vector<vpii>
#define vvi vector<vi>
#define tiii tuple<int, int, int>
#define vtiii vector<tiii>

#define sz(x) ((int)(x).size())
#define all(x) begin(x), end(x)

struct DSU
{
    vector<int> arr;
    vector<ll> sum;
    vvi nodes;
    void init(vi &s)
    {
        arr.resize(sz(s)), sum.resize(sz(s)), nodes.resize(sz(s));
        for (int i = 0; i < sz(s); ++i)
            arr[i] = i, sum[i] = s[i], nodes[i].push_back(i);
    }
    int find(int i)
    {
        if (arr[i] == i)
            return i;
        return arr[i] = find(arr[i]);
    }
    void clear(int i)
    {
        i = find(i);
        nodes[i].clear();
    }
    void join(int a, int b)
    {
        a = find(a);
        b = find(b);
        if (a == b)
            return;
        if (sz(nodes[a]) > sz(nodes[b]))
            swap(a, b);
        sum[b] += sum[a];
        for (int x : nodes[a])
            nodes[b].push_back(x);
        nodes[a].clear();
        arr[a] = b;
    }
    ll getsum(int i)
    {
        i = find(i);
        return sum[i];
    }
    void answer(int i, vi &ans)
    {
        i = find(i);
        for (int j : nodes[i])
            ans[j] = true;
    }
};

int main()
{
    ios::sync_with_stdio(false);
    cout.tie(0);
    cin.tie(0);

    int n, m;
    cin >> n >> m;
    vi s(n);
    vvi adj(n);
    for (int i = 0; i < n; ++i)
        cin >> s[i];
    for (int i = 0, a, b; i < m; ++i)
    {
        cin >> a >> b;
        --a, --b;
        adj[a].push_back(b);
        adj[b].push_back(a);
    }
    vi order(n);
    iota(all(order), 0);
    sort(all(order), [&](ll &a, ll &b)
         { return s[a] < s[b]; });

    DSU dsu;
    dsu.init(s);
    for (int v : order)
    {
        for (int w : adj[v])
        {
            if (s[w] > s[v])
                continue; // neighbor is larger, I will go the other direction later
            if (dsu.getsum(w) < s[v])
            { // the nodes of the other subtree aren't enough to spread their tie
                dsu.clear(w);
            }
            dsu.join(w, v);
        }
        /*
        for (int tmp = 0; tmp < n; ++tmp)
        {
            cout << tmp << " : (" << dsu.find(tmp) << ") : " << dsu.getsum(tmp) << " mit ";
            for (int w : dsu.nodes[dsu.find(tmp)])
                cout << " " << w;
            cout << endl;
        }
        */
    }

    vi ans(n, 0);
    dsu.answer(order.back(), ans);
    for (int x : ans)
        cout << x;
    cout << endl;
}

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