oj.uz

Submission #503750

# Submission time Handle Problem Language Result Execution time Memory
503750 2022-01-08T20:45:06 Z tabr Islands (IOI08_islands) C++17
80 / 100
 501 ms 131076 KB 
#include <bits/stdc++.h>
using namespace std;
#ifdef tabr
#include "library/debug.cpp"
#else
#define debug(...)
#endif

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);
    for (int i = 0; i < n; i++) {
        int j;
        cin >> j >> l[i];
        j--;
        e[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]);
        }
    }
    long long ans = 0;
    vector<int> was(n);
    vector<int> pv(n);
    vector<int> cycle(n);
    vector<int> cnt2(n);
    vector<long long> now2(n);
    for (int i = 0; i < n; i++) {
        if (was[i]) {
            continue;
        }
        int c1 = -1, c2 = -1;
        int sz = 0;
        int dead = -1;
        function<void(int, int)> dfs1 = [&](int v, int pe) {
            was[v] = 1;
            for (auto id : g[v]) {
                if (id == pe) {
                    continue;
                }
                int to = v ^ id ^ e[id];
                if (was[to]) {
                    if (c1 != -1) {
                        continue;
                    }
                    dead = id;
                    c1 = v;
                    c2 = to;
                    debug(c1, c2);
                    cycle[v]++;
                    if (pv[to] != -1) {
                        cycle[pv[to]]--;
                    }
                    continue;
                }
                pv[to] = v;
                dfs1(to, id);
                cycle[v] += cycle[to];
            }
            sz += cycle[v];
        };
        pv[i] = -1;
        dfs1(i, -1);
        vector<long long> d1(sz + 1), d2(sz + 1);
        function<void(int, int)> dfs2 = [&](int v, int p) {
            cnt2[v] += cycle[v];
            d1[cnt2[v]] = max(d1[cnt2[v]], now2[v]);
            for (auto id : g[v]) {
                int to = v ^ id ^ e[id];
                if (to == p || id == dead) {
                    continue;
                }
                cnt2[to] = cnt2[v];
                now2[to] = now2[v] + l[id];
                dfs2(to, v);
            }
        };
        now2[c1] = cnt2[c1] = 0;
        dfs2(c1, c2);
        swap(d1, d2);
        now2[c2] = cnt2[c2] = 0;
        dfs2(c2, c1);
        swap(d1, d2);
        for (int j = 0; j < sz; j++) {
            d1[j + 1] = max(d1[j + 1], d1[j]);
            d2[j + 1] = max(d2[j + 1], d2[j]);
        }
        long long t = 0;
        function<long long(int, int)> dfs3 = [&](int v, int p) {
            vector<long long> c;
            for (auto id : g[v]) {
                int to = v ^ id ^ e[id];
                if (to == p || id == dead) {
                    continue;
                }
                now2[to] = now2[v] + l[id];
                c.emplace_back(dfs3(to, v));
            }
            t = max(t, now2[v]);
            if (c.empty()) {
                return now2[v];
            }
            sort(c.rbegin(), c.rend());
            if (c.size() > 1) {
                t = max(t, c[0] + c[1] - 2 * now2[v]);
            }
            return c[0];
        };
        now2[c1] = 0;
        dfs3(c1, c2);
        now2[c2] = 0;
        dfs3(c2, c1);
        debug(t);
        debug(d1);
        debug(d2);
        for (int j = 1; j < sz; j++) {
            t = max(t, d1[j] + d2[sz - j] + l[dead]);
        }
        ans += t;
    }
    cout << ans << '\n';
    return 0;
}

Subtask #1
33.0 / 33.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 204 KB Output is correct
2 Correct 1 ms 332 KB Output is correct
3 Correct 1 ms 332 KB Output is correct
4 Correct 0 ms 204 KB Output is correct
5 Correct 1 ms 224 KB Output is correct
6 Correct 1 ms 204 KB Output is correct
7 Correct 0 ms 204 KB Output is correct
8 Correct 0 ms 204 KB Output is correct
9 Correct 1 ms 204 KB Output is correct
10 Correct 1 ms 204 KB Output is correct
11 Correct 0 ms 204 KB Output is correct

Subtask #2
3.0 / 3.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 460 KB Output is correct
2 Correct 1 ms 332 KB Output is correct

Subtask #3
4.0 / 4.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 460 KB Output is correct
2 Correct 3 ms 972 KB Output is correct

Subtask #4
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 13 ms 1852 KB Output is correct
2 Correct 48 ms 5880 KB Output is correct
3 Correct 17 ms 2136 KB Output is correct
4 Correct 8 ms 1228 KB Output is correct

Subtask #5
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 34 ms 8168 KB Output is correct
2 Correct 59 ms 12004 KB Output is correct

Subtask #6
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 136 ms 21628 KB Output is correct
2 Correct 141 ms 31872 KB Output is correct
3 Correct 160 ms 48148 KB Output is correct

Subtask #7
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 186 ms 37380 KB Output is correct
2 Correct 283 ms 80896 KB Output is correct
3 Correct 323 ms 92624 KB Output is correct
4 Correct 421 ms 123400 KB Output is correct

Subtask #8
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 501 ms 98708 KB Output is correct
2 Runtime error 442 ms 131076 KB Execution killed with signal 9
3 Halted 0 ms 0 KB -

Subtask #9
0 / 10.0

# Verdict Execution time Memory Grader output
1 Runtime error 352 ms 131076 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -