oj.uz

답안 #503778

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
503778 2022-01-08T21:48:01 Z tabr Islands (IOI08_islands) C++17
80 / 100
 614 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> last_id(n);
    for (int i = 0; i < n; i++) {
        if (was[i]) {
            continue;
        }
        int c1 = -1, c2 = -1;
        int sz = 0;
        int dead = -1;
        pv[i] = -1;
        {  // dfs1
            stack<pair<int, int>> stk;
            stk.emplace(i, -1);
            while (!stk.empty()) {
                auto [v, pe] = stk.top();
                was[v] = 1;
                debug(v);
                if (last_id[v] == (int) g[v].size()) {
                    for (auto id : g[v]) {
                        int to = v ^ id ^ e[id];
                        if (to == pv[v]) {
                            continue;
                        }
                        cycle[v] += cycle[to];
                    }
                    if (v == c1 || v == c2) {
                        cycle[v] = 1;
                    }
                    sz += cycle[v];
                    stk.pop();
                    continue;
                }
                int &gid = last_id[v];
                while (gid < (int) g[v].size()) {
                    int id = g[v][gid++];
                    if (id == pe) {
                        continue;
                    }
                    int to = v ^ id ^ e[id];
                    if (was[to]) {
                        debug(v, to);
                        if (c1 != -1) {
                            continue;
                        }
                        dead = id;
                        c1 = v;
                        c2 = to;
                        cycle[v]++;
                        if (pv[to] != -1) {
                            cycle[pv[to]]--;
                        }
                        continue;
                    }
                    pv[to] = v;
                    stk.emplace(to, id);
                    break;
                }
            }
        }
        debug(cycle);
        vector<long long> d1(sz + 1), d2(sz + 1);
        function<void(int, int, int, long long)> dfs2 = [&](int v, int p, int cnt, long long now) {
            cnt += cycle[v];
            d1[cnt] = max(d1[cnt], now);
            for (auto id : g[v]) {
                int to = v ^ id ^ e[id];
                if (to == p || id == dead) {
                    continue;
                }
                dfs2(to, v, cnt, now + l[id]);
            }
        };
        dfs2(c1, c2, 0, 0);
        swap(d1, d2);
        dfs2(c2, c1, 0, 0);
        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, long long)> dfs3 = [&](int v, int p, long long now) {
            array<long long, 3> c = {-1, -1, -1};
            for (auto id : g[v]) {
                int to = v ^ id ^ e[id];
                if (to == p || id == dead) {
                    continue;
                }
                c[2] = dfs3(to, v, now + l[id]);
                sort(c.rbegin(), c.rend());
            }
            t = max(t, now);
            if (c[0] == -1) {
                return now;
            }
            if (c[1] > -1) {
                t = max(t, c[0] + c[1] - 2 * now);
            }
            return c[0];
        };
        dfs3(c1, c2, 0);
        dfs3(c2, c1, 0);
        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

# 결과 실행 시간 메모리 Grader output
1 Correct 0 ms 204 KB Output is correct
2 Correct 0 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 0 ms 204 KB Output is correct
6 Correct 0 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 0 ms 204 KB Output is correct
10 Correct 0 ms 204 KB Output is correct
11 Correct 0 ms 204 KB Output is correct

Subtask #2
3.0 / 3.0

# 결과 실행 시간 메모리 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

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 396 KB Output is correct
2 Correct 3 ms 972 KB Output is correct

Subtask #4
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 10 ms 1868 KB Output is correct
2 Correct 22 ms 5728 KB Output is correct
3 Correct 16 ms 1996 KB Output is correct
4 Correct 6 ms 1164 KB Output is correct

Subtask #5
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 30 ms 7748 KB Output is correct
2 Correct 40 ms 11296 KB Output is correct

Subtask #6
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 105 ms 19716 KB Output is correct
2 Correct 112 ms 31196 KB Output is correct
3 Correct 143 ms 45784 KB Output is correct

Subtask #7
10.0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 173 ms 34500 KB Output is correct
2 Correct 228 ms 73952 KB Output is correct
3 Correct 289 ms 92272 KB Output is correct
4 Correct 316 ms 117288 KB Output is correct

Subtask #8
0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Correct 325 ms 82464 KB Output is correct
2 Runtime error 614 ms 131076 KB Execution killed with signal 9
3 Halted 0 ms 0 KB -

Subtask #9
0 / 10.0

# 결과 실행 시간 메모리 Grader output
1 Runtime error 333 ms 131076 KB Execution killed with signal 9
2 Halted 0 ms 0 KB -