Submission #701234

#	Time	Username	Problem	Language	Result	Execution time	Memory
701234		tamthegod	Zagrade (COI17_zagrade)	C++17	100 / 100	1196 ms	75048 KiB

zagrade

// Make the best become better
// No room for laziness
#include<bits/stdc++.h>

#define int long long
#define pb push_back
#define fi first
#define se second
using namespace std;
using ll = long long;
using ld = long double;
using ull = unsigned long long;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const int maxN = 1e6 + 5;
const int mod = 1e9 + 7;
const ll oo = 1e18;
int n;
string s;
vector<int> adj[maxN];
int sz[maxN];
int vis[maxN];
int valid[maxN], valid1[maxN];
pair<int, int> f[maxN], dp[maxN];
int a[maxN];
int res = 0;
int cnt[maxN];
void ReadInput()
{
    cin >> n;
    cin >> s;
    s = ' ' + s;
    for(int i=1; i<=n; i++)
        a[i] = (s[i] == '(' ? 1 : -1);
    for(int i=1; i<n; i++)
    {
        int u, v;
        cin >> u >> v;
        adj[u].pb(v);
        adj[v].pb(u);
    }
}
int dfs(int u, int par)
{
    sz[u] = 1;
    for(int v : adj[u])
    {
        if(v == par || vis[v]) continue;
        sz[u] += dfs(v, u);
    }
    return sz[u];
}
int Find_Centroid(int u, int par, int _sz)
{
    for(int v : adj[u])
    {
        if(v == par || vis[v]) continue;
        if(sz[v] > _sz / 2) return Find_Centroid(v, u, _sz);
    }
    return u;
}
void DFS(int u, int par)
{
    f[u].fi = f[par].fi + a[u];
    f[u].se = max(f[u].fi, f[par].se);
    dp[u].fi = f[u].fi;
    dp[u].se = min(dp[par].se, dp[u].fi);
    valid[u] = f[u].fi >= f[par].se;
    valid1[u] = dp[u].fi <= dp[par].se;
    if(valid1[u]) cnt[-dp[u].fi]++;
    if(valid1[u] && !f[u].fi) res++;
    for(int v : adj[u])
    {
        if(vis[v] || v == par) continue;
        DFS(v, u);
    }
}
void del(int u, int par)
{
    if(valid1[u]) cnt[-dp[u].fi]--;
    for(int v : adj[u])
    {
        if(vis[v] || v == par) continue;
        del(v, u);
    }
}
int root;
void upd(int u, int par)
{
    if(valid[u]) res += cnt[f[u].fi - a[root]];
    for(int v : adj[u])
    {
        if(vis[v] || v == par) continue;
        upd(v, u);
    }
}
void add(int u, int par)
{
    if(valid1[u]) cnt[-dp[u].fi]++;
    for(int v : adj[u])
    {
        if(vis[v] || v == par) continue;
        add(v, u);
    }
}
void Decompose(int u)
{
    root = Find_Centroid(u, 0, dfs(u, 0));
    vis[root] = 1;
    f[u] = {0, 0};
    DFS(root, 0);
    for(int v : adj[root])
    {
        if(vis[v]) continue;
        del(v, root);
        upd(v, root);
        add(v, root);
    }
    del(root, 0);
    for(int v : adj[root])
    {
        if(vis[v]) continue;
        Decompose(v);
    }
}
void Solve()
{
    Decompose(1);
    cout << res;
}
int32_t main()
{
    //freopen("sol.inp", "r", stdin);
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    ReadInput();
    Solve();
}

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