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ID题目提交者结果用时内存语言文件大小提交时间测评时间
#150117#5421. Factories Once MorergnerdplayerTL 1ms3544kbC++203.2kb2023-08-25 15:18:132023-08-25 15:18:14

Judging History

你现在查看的是最新测评结果

  • [2023-08-25 15:18:14]
  • 评测
  • 测评结果:TL
  • 用时:1ms
  • 内存:3544kb
  • [2023-08-25 15:18:13]
  • 提交

answer

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

using i64 = long long;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

struct Treap {
    Treap *lc = nullptr, *rc = nullptr;
    int sz = 1;
    unsigned w = rng();
    i64 m = 0, b = 0, val = 0;
};

int size(Treap *t) {
    return t == nullptr ? 0 : t->sz;
}
void apply(Treap *t, i64 m, i64 b) {
    t->m += m;
    t->b += b;
    t->val += m * size(t->lc) + b;
}
void pull(Treap *t) {
    t->sz = size(t->lc) + size(t->rc) + 1;
}
void push(Treap *t) {
    if (t->lc != nullptr) {
        apply(t->lc, t->m, t->b);
    }
    if (t->rc != nullptr) {
        apply(t->rc, t->m, t->b + t->m * (size(t->lc) + 1));
    }
    t->m = t->b = 0;
}

pair<Treap*, Treap*> split(Treap *t, int s) {
    if (t == nullptr) { return {t, t}; }
    push(t);
    Treap *a, *b;
    if (s <= size(t->lc)) {
        b = t;
        tie(a, b->lc) = split(t->lc, s);
    } else {
        a = t;
        tie(a->rc, b) = split(t->rc, s - size(t->lc) - 1);
    }
    pull(t);
    return {a, b};
}

Treap* merge(Treap *t1, Treap *t2) {
    if (t1 == nullptr) { return t2; }
    if (t2 == nullptr) { return t1; }
    push(t1), push(t2);
    if (t1->w > t2->w) {
        t1->rc = merge(t1->rc, t2);
        pull(t1);
        return t1;
    } else {
        t2->lc = merge(t1, t2->lc);
        pull(t2);
        return t2;
    }
}

int rnk(Treap *t, i64 val) {
    int res = 0;
    while (t != nullptr) {
        if (val <= t->val) {
            res += size(t->lc) + 1;
            t = t->rc;
        } else {
            t = t->lc;
        }
    }
    return res;
}

Treap* join(Treap *t1, Treap *t2) {
    Treap *t = nullptr;
    while (t1 != nullptr) {
        auto [u1, v1] = split(t1, 1);
        t1 = v1;
        int r = rnk(t2, u1->val);
        if (r > 0) {
            auto [u2, v2] = split(t2, r);
            t = merge(t, u2);
            t2 = v2;
        }
        t = merge(t, u1);
    }
    t = merge(t, t2);
    return t;
}

int main() {
    cin.tie(nullptr)->sync_with_stdio(false);
    
    auto solve = [&]() {
        int n, k;
        cin >> n >> k;

        vector<vector<pair<int, int>>> adj(n);
        for (int i = 1; i < n; i++) {
            int u, v, w;
            cin >> u >> v >> w;
            u--, v--;
            adj[u].emplace_back(v, w);
            adj[v].emplace_back(u, w);
        }
        
        // dp[u][x] = max_{i + j = x} (dp[u][i] + dp[v][j] + w * j * (k - j))
        // dp[u][0] = dp[u][1] = 0
        // maintain slope ? ;

        auto dfs = [&](auto dfs, int u, int p) -> Treap* {
            Treap *tu = new Treap;
            for (auto [v, w] : adj[u]) {
                if (v == p) {
                    continue;
                }
                auto tv = dfs(dfs, v, u);
                apply(tv, -2 * w, 1LL * (k - 1) * w);
                tu = join(tu, tv);
            }
            return tu;
        };
        auto t = dfs(dfs, 0, -1);

        i64 ans = 0;

        while (k--) {
            auto [u, v] = split(t, 1);
            ans += u->val;
            t = v;
        }

        cout << ans << '\n';
    };

    solve();

    return 0;
}


詳細信息

Test #1:

score: 100
Accepted
time: 1ms
memory: 3496kb

input:

6 3
1 2 3
2 3 2
2 4 1
1 5 2
5 6 3

output:

22

result:

ok 1 number(s): "22"

Test #2:

score: 0
Accepted
time: 1ms
memory: 3544kb

input:

4 3
1 2 2
1 3 3
1 4 4

output:

18

result:

ok 1 number(s): "18"

Test #3:

score: 0
Accepted
time: 1ms
memory: 3488kb

input:

2 2
1 2 1

output:

1

result:

ok 1 number(s): "1"

Test #4:

score: -100
Time Limit Exceeded

input:

100000 17
37253 35652 9892
56367 53643 1120
47896 49255 4547
93065 88999 1745
5251 6742 5031
49828 50972 8974
31548 46729 1032
56341 56287 4812
21896 22838 1682
82124 90557 7307
76289 76949 7028
33834 45380 6856
15499 15064 2265
10127 5251 9920
87208 93945 9487
68990 72637 6891
91640 85004 2259
4748...

output:


result: