Submission #969189

#	Time	Username	Problem	Language	Result	Execution time	Memory
969189		Beerus13	Zagrade (COI17_zagrade)	C++14	100 / 100	786 ms	39944 KiB

zagrade

#include<bits/stdc++.h>
using namespace std;
#define ll long long
const int N = 3e5 + 5;

int n, a[N], sz[N], cnt[N];
bool del[N];
vector<int> g[N];
ll ans;

int dfs_size(int u, int p = 0) {
    sz[u] = 1;
    for(int v : g[u]) if(v != p && !del[v]) sz[u] += dfs_size(v, u);
    return sz[u];
}

int find_centroid(int u, int p, int num) {
    for(int v : g[u]) if(v != p && !del[v] && sz[v] > num / 2) return find_centroid(v, u, num);
    return u;
}

void dfs_open(int u, int p = 0, int val = 0, int num_close = 0) {
    num_close = max(num_close, 0);
    if(a[u] == -1) ++num_close;
    else --num_close;
    val += a[u];
    if(num_close <= 0) {
        ans += cnt[val];
    }
    for(int v : g[u]) if(v != p && !del[v]) {
        dfs_open(v, u, val, num_close);
    }
}

void dfs_close(int add, int u, int p = 0, int val = 0, int num_open = 0) {
    num_open = max(num_open, 0);
    if(a[u] == 1) {
        ++num_open;
        --val;
    }
    else {
        --num_open;
        ++val;
    }
    if(num_open <= 0) {
        cnt[val] += add;
    }
    for(int v : g[u]) if(v != p && !del[v]) {
        dfs_close(add, v, u, val, num_open);
    }
}

void decomposition(int u) {
    u = find_centroid(u, 0, dfs_size(u));
    del[u] = 1;
    dfs_close(1, u);
    ans += cnt[0];
    for(int v : g[u]) if(!del[v]) {
        dfs_close(-1, v, u, -a[u], a[u]);
        dfs_open(v, u);
        dfs_close(1, v, u, -a[u], a[u]);
    }
    dfs_close(-1, u);
    for(int v : g[u]) if(!del[v]) {
        decomposition(v);
    }
}

void solve() {
    cin >> n;
    string s; cin >> s;
    for(int i = 0; i < s.size(); ++i) {
        a[i + 1] = s[i] == '(' ? 1 : -1;
    }
    for(int i = 1, u, v; i < n; ++i) {
        cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    decomposition(1);
    cout << ans << '\n';
}


signed main() {
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    int test = 1;
    // cin >> test;
    while(test--) solve();
    return 0;
}

// https://oj.uz/problem/view/COI17_zagrade

Compilation message (stderr)

zagrade.cpp: In function 'void solve()':
zagrade.cpp:72:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   72 |     for(int i = 0; i < s.size(); ++i) {
      |                    ~~^~~~~~~~~~

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