Submission #673888

#TimeUsernameProblemLanguageResultExecution timeMemory
673888Sam_a17Shymbulak (IZhO14_shymbulak)C++17
100 / 100
104 ms22172 KiB
#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
// #include "temp.cpp"
#include <cstdio>
using namespace std;
 
#ifndef ONLINE_JUDGE
#define dbg(x) cerr << #x <<" "; print(x); cerr << endl;
#else
#define dbg(x)
#endif
 
#define sz(x) (int((x).size()))
#define len(x) (int)x.length()
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define clr(x) x.clear()
#define uniq(x) x.resize(unique(all(x)) - x.begin());
#define blt __builtin_popcount
 
#define pb push_back
#define pf push_front
#define popf pop_front
#define popb pop_back
 
void print(long long t) {cerr << t;}
void print(int t) {cerr << t;}
void print(string t) {cerr << t;}
void print(char t) {cerr << t;}
void print(double t) {cerr << t;}
void print(long double t) {cerr << t;}
void print(unsigned long long t) {cerr << t;}
 
template <class T> void print(set <T> v);
template <class T> void print(vector <T> v);
template <class T> void print(multiset <T> v);
template <class T, class V> void print(map <T, V> v);
template <class T, class V> void print(pair <T, V> p);
template <class T, class V> void print(T v[],V n) {cerr << "["; for(int i = 0; i < n; i++) {print(v[i]); cerr << " "; } cerr << "]";}
template <class T, class V> void print(pair <T, V> p) {cerr << "{"; print(p.first); cerr << ","; print(p.second); cerr << "}";}
template <class T> void print(vector <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(deque<T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(set <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(multiset <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T, class V> void print(map <T, V> v) {cerr << "[ "; for (auto i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T, class V> void print(unordered_map<T, V> v) {cerr << "[ "; for (auto i : v) {print(i); cerr << " ";} cerr << "]";}
 
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
#define nl '\n'
 
// for grid problems
int dx[8] = {-1,0,1,0,1,-1,1,-1};
int dy[8] = {0,1,0,-1,1,1,-1,-1};
 
// lowest / (1 << 17) >= 1e5 / (1 << 18) >= 2e5 / (1 << 21) >= 1e6
void fastIO() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr); cout.tie(nullptr);
}
 
// file in/out
void setIO(string str = "") {
  fastIO();
 
  if (str != "" && str != "input") {
    freopen((str + ".in").c_str(), "r", stdin);
    freopen((str + ".out").c_str(), "w", stdout);
  }
 
  if(str == "input") {
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
  }
}
// Indexed Set
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
const long long inf = 1e15;
const int N = 2e5 + 10;
vector<int> adj[N];
 
pair<long long, long long> combine(pair<long long, long long> a, pair<long long, long long> b) {
  if(a.first == b.first) {
    a.second += b.second;
    return a;
  } else if(a.first > b.first) {
    return a;
  } else {
    return b;
  }
}
 
// for cycle
bool in_cycle[N];
int n, vis[N], p[N];
vector<int> cycle;
bool is_cycle = false;
 
void dfsCycle(int node, int parent) {
  vis[node] = 1, p[node] = parent;
  for(auto i: adj[node]) {
    if(i == parent) continue;
 
    if(vis[i] == 1) {
      int curr = node;
      while(curr != i) {
        cycle.push_back(curr);
        curr = p[curr];
      }
      cycle.push_back(curr);
      is_cycle = true;
      return;
    } else if(!vis[i]) {
      dfsCycle(i, node);
    }
 
    if(is_cycle) {
      return;
    }
  }
  vis[node] = 2;
}
 
// for trees
pair<long long, long long> dp[N];
pair<long long, long long> ans = {0, 0};
 
void dfs_depth(int node, int parent) {
  dp[node] = {0, 1};
 
  int cnt = 0;
  for(auto i: adj[node]) {
    if(i == parent || in_cycle[i]) continue;
    dfs_depth(i, node);
    cnt++;
    
 
    pair<long long, long long> sub = dp[i];
    sub.first++;
    if(cnt == 1) {
      dp[node] = sub;
    }
    else {
      pair<long long, long long> sub_x = {dp[node].first + dp[i].first + 1, dp[node].second * dp[i].second};
      dp[node] = combine(dp[node], sub);
      ans = combine(ans, sub_x);
    }
    ans = combine(ans, dp[node]);
  }
}
 
void solve_() {
  cin >> n;
 
  for(int i = 1; i <= n; i++) {
    int a, b; cin >> a >> b;
    adj[a].push_back(b);
    adj[b].push_back(a);
  }
 
  dfsCycle(1, 0);
 
  for(auto i: cycle) {
    in_cycle[i] = true;
  }
 
  for(auto i: cycle) {
    dfs_depth(i, 0);
  }
 
  int sz = sz(cycle);
  set<pair<long long, long long>> st;
  for(int i = 0; i < sz + sz / 2; i++) {
    if(i >= sz / 2) {
      pair<long long, long long> curr = {dp[cycle[i % sz]].first + i + st.rbegin()->first, 0};
      ans = combine(ans, curr);
      st.erase({dp[cycle[i - sz / 2]].first - (i - sz / 2), i - sz / 2});
    }
    st.insert({dp[cycle[i % sz]].first - i, i});
  }
 
  map<long long, long long> mp;
  for(int i = 0; i < sz + sz / 2; i++) {
    if(i >= sz / 2) {
      long long to_find = ans.first - (dp[cycle[i % sz]].first + i);
      ans.second += mp[to_find] * dp[cycle[i % sz]].second;
      mp[dp[cycle[i - sz / 2]].first - (i - sz / 2)] -= dp[cycle[i - sz / 2]].second;
    }
    mp[dp[cycle[i % sz]].first - i] += dp[cycle[i % sz]].second;
  }
 
  cout << ans.second << '\n';
}
 
int main() {
  setIO();
 
  auto solve = [&](int test_case)-> void {
    while(test_case--) {
      solve_();
    }
  };
 
  int test_cases = 1;
  // cin >> test_cases;
  solve(test_cases);
 
  return 0;
} 

Compilation message (stderr)

shymbulak.cpp: In function 'void setIO(std::string)':
shymbulak.cpp:67:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   67 |     freopen((str + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
shymbulak.cpp:68:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   68 |     freopen((str + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
shymbulak.cpp:72:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   72 |     freopen("input.txt", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
shymbulak.cpp:73:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   73 |     freopen("output.txt", "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
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