Submission #503743

#	Time	Username	Problem	Language	Result	Execution time	Memory
503743		tabr	Islands (IOI08_islands)	C++17	40 / 100	2097 ms	131076 KiB

islands

#include <bits/stdc++.h>
using namespace std;
#ifdef tabr
#include "library/debug.cpp"
#else
#define debug(...)
#endif

struct dsu {
    vector<int> p;
    vector<int> sz;
    int n;

    dsu(int _n) : n(_n) {
        p.resize(n);
        iota(p.begin(), p.end(), 0);
        sz.assign(n, 1);
    }

    inline int get(int x) {
        if (p[x] == x) {
            return x;
        } else {
            return p[x] = get(p[x]);
        }
    }

    inline bool unite(int x, int y) {
        x = get(x);
        y = get(y);
        if (x == y) {
            return false;
        }
        if (sz[x] > sz[y]) {
            swap(x, y);
        }
        p[x] = y;
        sz[y] += sz[x];
        return true;
    }

    inline bool same(int x, int y) {
        return (get(x) == get(y));
    }
};

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin >> n;
    vector<vector<int>> g(n);
    vector<int> l(n);
    vector<int> e(n);
    dsu uf(n);
    for (int i = 0; i < n; i++) {
        int j;
        cin >> j >> l[i];
        j--;
        e[i] = j;
        uf.unite(i, j);
        g[i].emplace_back(i);
        g[j].emplace_back(i);
    }
    for (int i = 0; i < n; i++) {
        if (e[e[i]] == i) {
            l[e[i]] = l[i] = max(l[e[i]], l[i]);
        }
    }
    vector<long long> a(n);
    vector<int> b(n);
    for (int i = 0; i < n; i++) {
        long long t = 0;
        function<void(int, int, long long)> dfs = [&](int v, int p, long long now) {
            b[v] = 1;
            t = max(t, now);
            for (int id : g[v]) {
                int to = v ^ id ^ e[id];
                if (to == p || b[to]) {
                    continue;
                }
                dfs(to, v, now + l[id]);
            }
            b[v] = 0;
        };
        dfs(i, -1, 0);
        a[uf.get(i)] = max(a[uf.get(i)], t);
    }
    cout << accumulate(a.begin(), a.end(), 0LL) << '\n';
    return 0;
}

• Subtask 1: 33 / 33
• Subtask 2: 3 / 3
• Subtask 3: 4 / 4
• Subtask 4: 0 / 10
• Subtask 5: 0 / 10
• Subtask 6: 0 / 10
• Subtask 7: 0 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 10