Submission #553083

#	Time	Username	Problem	Language	Result	Execution time	Memory
553083		hoanghq2004	Zagrade (COI17_zagrade)	C++14	100 / 100	1086 ms	54492 KiB

zagrade

#include <bits/stdc++.h>
#pragma GCC optimize ("O3")
#pragma GCC optimize ("unroll-loops")
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace __gnu_pbds;
using namespace std;

template <typename T>
using ordered_set = tree <T, null_type, less <T>, rb_tree_tag, tree_order_statistics_node_update>;

const int N = 3e5 + 10;

int n, sz[N], big[N], c[N], del[N];
vector <int> g[N];

void dfs(int u, int p) {
    sz[u] = 1, big[u] = 0;
    for (auto v: g[u]) {
        if (v == p || del[v]) continue;
        dfs(v, u);
        sz[u] += sz[v];
        if (sz[v] >= sz[big[u]]) big[u] = v;
    }
}

int cnt[N * 2];

int centroid(int u) {
    dfs(u, 0);
    int num = sz[u] / 2;
    while (sz[big[u]] > num) u = big[u];
    return u;
}

void add(int u, int p, int s, int d) {
    if (d >= 0) ++cnt[s + N];
    for (auto v: g[u]) {
        if (v == p || del[v]) continue;
        add(v, u, s + c[v], min(d + c[v], c[v]));
    }
}

long long ans;

void calc(int u, int p, int s, int d) {
    if (d >= s) ans += cnt[N - s];
    for (auto v: g[u]) {
        if (v == p || del[v]) continue;
        calc(v, u, s + c[v], min(d, s + c[v]));
    }
}


void rev(int u, int p, int s, int d) {
    if (d >= 0) --cnt[s + N];
    for (auto v: g[u]) {
        if (v == p || del[v]) continue;
        rev(v, u, s + c[v], min(d + c[v], c[v]));
    }
}

void build(int u) {
    u = centroid(u);
    if (c[u] >= 0) ++cnt[c[u] + N];
    for (auto v: g[u]) {
        if (del[v]) continue;
        calc(v, u, c[v], min(0, c[v]));
        add(v, u, c[u] + c[v], min({0, c[u] + c[v], c[v]}));
    }
    for (auto v: g[u]) {
        if (del[v]) continue;
        rev(v, u, c[u] + c[v], min({0, c[u] + c[v], c[v]}));
    }
    if (c[u] >= 0) --cnt[c[u] + N];
    reverse(g[u].begin(), g[u].end());
    for (auto v: g[u]) {
        if (del[v]) continue;
        calc(v, u, c[v], min(0, c[v]));
        add(v, u, c[u] + c[v], min({0, c[u] + c[v], c[v]}));
    }
    ans += cnt[N];
    for (auto v: g[u]) {
        if (del[v]) continue;
        rev(v, u, c[u] + c[v], min({0, c[u] + c[v], c[v]}));
    }
    del[u] = 1;
    for (auto v: g[u])
        if (!del[v]) build(v);
}

int main() {
    ios :: sync_with_stdio(0); cin.tie(0);
    cin >> n;
    for (int u = 1; u <= n; ++u) {
        char ch;
        cin >> ch;
        c[u] = (ch == '(' ? 1 : -1);
    }
    for (int i = 1; i < n; ++i) {
        int u, v;
        cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    build(1);
    cout << ans;
}

• Subtask 1: 10 / 10
• Subtask 2: 30 / 30
• Subtask 3: 60 / 60