Submission #869085

#	Time	Username	Problem	Language	Result	Execution time	Memory
869085		NeroZein	Zagrade (COI17_zagrade)	C++17	0 / 100	289 ms	47448 KiB

zagrade

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

#ifdef Nero
#include "Deb.h"
#else
#define deb(...)
#endif

const int N = 3e5 + 5;

int a[N]; 
int sz[N];
int cent; 
long long ans; 
bool block[N]; 
vector<int> g[N]; 
int cntp[N], cntn[N];

void get_size(int v, int p) {
  sz[v] = 1; 
  for (int u : g[v]) {
    if (!block[u] && u != p) {
      get_size(u, v);
      sz[v] += sz[u]; 
    }
  }
}

int get_centroid(int v, int p, int x) {
  int ret = v;
  for (int u : g[v]) {
    if (!block[u] && u != p && sz[u] > x / 2) {
      return get_centroid(u, v, x); 
    }
  }
  return ret;
}

void dfs(int v, int p, int sum, int min_pref, int min_suf, int upd) {
  //deb(v) deb(cent) deb(sum) 
  sum += a[v];
  //deb(sum) cout << '\n';
  min_pref = min(min_pref, sum); 
  min_suf = min(0, min_suf + a[v]); 
  if (upd) {
    if (sum < 0 && min_pref == sum) {
      cntn[-sum] += upd; 
      //deb(v) deb(cent) deb(sum) cout << '\n';
    } else if (sum >= 0 && min_suf == 0) {
      //deb(v) deb(cent) deb(sum) cout << '\n';
      cntp[sum] += upd; 
    }
  } else {
    if (sum == 0 && (min_pref == 0 || min_suf == 0)) {
      ans++; 
    }
    int tsum = sum - a[cent]; 
    int tpref = min(0, min_pref - a[cent]); 
    if (tsum < 0 && tpref == tsum) {
      //deb(v) deb(cent) de b(tsum) deb(tpref) deb(cntp[-tsum]) cout << '\n';
      ans += cntp[-tsum];
    } else if (tsum >= 0 && min_suf == 0) {
      //deb(v) deb(cent) cout << '\n';
      ans += cntn[tsum]; 
    }
  }
  for (int u : g[v]) {
    if (!block[u] && u != p) {
      //deb(v) deb(u) deb(sum) cout << '\n';
      dfs(u, v, sum, min_pref, min_suf, upd); 
    }
  }
}

void init(int root) {
  get_size(root, root); 
  cent = get_centroid(root, root, sz[root]); 
  block[cent] = true;
  for (int u : g[cent]) {
    if (!block[u]) {
      dfs(u, cent, a[cent], min(0, a[cent]), min(0, a[cent]), 0); 
      dfs(u, cent, a[cent], min(0, a[cent]), min(0, a[cent]), 1); 
    }
  }
  for (int u : g[cent]) {
    if (!block[u]) {
      dfs(u, cent, a[cent], min(0, a[cent]), min(0, a[cent]), -1); 
    }
  }
  for (int u : g[cent]) {
    if (!block[u]) {
      init(u); 
    }
  }
}

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

• Subtask 1: 0 / 10
• Subtask 2: 0 / 30
• Subtask 3: 0 / 60