結果

問題 No.1424 Ultrapalindrome
ユーザー hamrayhamray
提出日時 2021-03-18 16:21:09
言語 C++14
(gcc 12.3.0 + boost 1.83.0)
結果
AC  
実行時間 39 ms / 2,000 ms
コード長 5,191 bytes
コンパイル時間 1,925 ms
コンパイル使用メモリ 184,024 KB
実行使用メモリ 9,772 KB
最終ジャッジ日時 2024-11-16 19:30:08
合計ジャッジ時間 3,673 ms
ジャッジサーバーID
（参考情報） 		judge1 / judge5
このコードへのチャレンジ
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テストケース

テストケース表示
入力 結果 実行時間
実行使用メモリ
testcase_00 AC 3 ms
5,632 KB
testcase_01 AC 4 ms
5,504 KB
testcase_02 AC 3 ms
5,632 KB
testcase_03 AC 4 ms
5,632 KB
testcase_04 AC 3 ms
5,632 KB
testcase_05 AC 4 ms
5,632 KB
testcase_06 AC 4 ms
5,632 KB
testcase_07 AC 4 ms
5,504 KB
testcase_08 AC 3 ms
5,632 KB
testcase_09 AC 33 ms
8,064 KB
testcase_10 AC 33 ms
8,064 KB
testcase_11 AC 23 ms
7,424 KB
testcase_12 AC 31 ms
7,808 KB
testcase_13 AC 10 ms
6,272 KB
testcase_14 AC 25 ms
7,424 KB
testcase_15 AC 4 ms
5,504 KB
testcase_16 AC 19 ms
7,040 KB
testcase_17 AC 23 ms
7,396 KB
testcase_18 AC 17 ms
6,912 KB
testcase_19 AC 24 ms
7,552 KB
testcase_20 AC 9 ms
6,144 KB
testcase_21 AC 21 ms
7,296 KB
testcase_22 AC 14 ms
6,656 KB
testcase_23 AC 5 ms
5,760 KB
testcase_24 AC 8 ms
6,016 KB
testcase_25 AC 6 ms
6,144 KB
testcase_26 AC 32 ms
8,064 KB
testcase_27 AC 39 ms
8,960 KB
testcase_28 AC 30 ms
8,576 KB
testcase_29 AC 30 ms
9,088 KB
testcase_30 AC 26 ms
9,772 KB
testcase_31 AC 29 ms
9,772 KB
権限があれば一括ダウンロードができます

ソースコード

diff # 

#include <bits/stdc++.h>
//#include <atcoder/all>
//using namespace atcoder;
#pragma GCC target ("avx")
#pragma GCC optimization ("O3")
#pragma GCC optimization ("unroll-loops")

using namespace std;

typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef pair<int, int> pii;
typedef pair<long long, long long> PLL;
typedef pair<int, PII> TIII;

typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;


#define FOR(i, s, n) for (int i = s; i < (int)n; ++i)
#define REP(i, n) FOR(i, 0, n)
#define rep(i, a, b) for (int i = a; i < (b); ++i)
#define trav(a, x) for (auto &a : x)
#define all(x) x.begin(), x.end()

#define MOD 1000000007

template<class T1, class T2> inline bool chmax(T1 &a, T2 b) {if (a < b) {a = b; return true;} return false;}
template<class T1, class T2> inline bool chmin(T1 &a, T2 b) {if (a > b) {a = b; return true;} return false;}
const double EPS = 1e-6, PI = acos(-1);
const double pi = 3.141592653589793238462643383279;
//ここから編集    
typedef string::const_iterator State;
ll GCD(ll a, ll b){
  return (b==0)?a:GCD(b, a%b);
}
ll LCM(ll a, ll b){
  return a/GCD(a, b) * b;
}
template< int mod >
struct ModInt {
  int x;

  ModInt() : x(0) {}

  ModInt(int64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}

  ModInt &operator+=(const ModInt &p) {
    if((x += p.x) >= mod) x -= mod;
    return *this;
  }

  ModInt &operator-=(const ModInt &p) {
    if((x += mod - p.x) >= mod) x -= mod;
    return *this;
  }

  ModInt &operator*=(const ModInt &p) {
    x = (int) (1LL * x * p.x % mod);
    return *this;
  }

  ModInt &operator/=(const ModInt &p) {
    *this *= p.inverse();
    return *this;
  }

  ModInt operator-() const { return ModInt(-x); }

  ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; }

  ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; }

  ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; }

  ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; }

  bool operator==(const ModInt &p) const { return x == p.x; }

  bool operator!=(const ModInt &p) const { return x != p.x; }

  ModInt inverse() const {
    int a = x, b = mod, u = 1, v = 0, t;
    while(b > 0) {
      t = a / b;
      swap(a -= t * b, b);
      swap(u -= t * v, v);
    }
    return ModInt(u);
  }

  ModInt pow(int64_t n) const {
    ModInt ret(1), mul(x);
    while(n > 0) {
      if(n & 1) ret *= mul;
      mul *= mul;
      n >>= 1;
    }
    return ret;
  }

  friend ostream &operator<<(ostream &os, const ModInt &p) {
    return os << p.x;
  }

  friend istream &operator>>(istream &is, ModInt &a) {
    int64_t t;
    is >> t;
    a = ModInt< mod >(t);
    return (is);
  }

  static int get_mod() { return mod; }
};

using modint = ModInt< 1000000007 >;
template< typename T >
struct Combination {
  vector< T > _fact, _rfact, _inv;

  Combination(int sz) : _fact(sz + 1), _rfact(sz + 1), _inv(sz + 1) {
    _fact[0] = _rfact[sz] = _inv[0] = 1;
    for(int i = 1; i <= sz; i++) _fact[i] = _fact[i - 1] * i;
    _rfact[sz] /= _fact[sz];
    for(int i = sz - 1; i >= 0; i--) _rfact[i] = _rfact[i + 1] * (i + 1);
    for(int i = 1; i <= sz; i++) _inv[i] = _rfact[i] * _fact[i - 1];
  }

  inline T fact(int k) const { return _fact[k]; }

  inline T rfact(int k) const { return _rfact[k]; }

  inline T inv(int k) const { return _inv[k]; }

  T P(int n, int r) const {
    if(r < 0 || n < r) return 0;
    return fact(n) * rfact(n - r);
  }

  T C(int p, int q) const {
    if(q < 0 || p < q) return 0;
    return fact(p) * rfact(q) * rfact(p - q);
  }

  T H(int n, int r) const {
    if(n < 0 || r < 0) return (0);
    return r == 0 ? 1 : C(n + r - 1, r);
  }
};

int modpow(ll x, ll n, int mod) {
  if(x == 0) return 0;
  
  ll res = 1;
  while(n) {
    if(n&1) res = res*x % mod;
    x = x*x%mod;
    n >>= 1;
  }
  return res;
}
vector<vector<int>> g(101010);
int depth[101010];
void dfs(int from, int v, ll dist, ll &maxd, int &maxv){

  depth[v] = dist;
  if(dist > maxd){
    maxd = dist;
    maxv = v;
  }
  for(auto u: g[v]){
    if(u == from) continue;
    dfs(v, u, dist + 1, maxd, maxv);
  }
}
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(7);
  
  int n; cin >> n;
  
  vector<int> cand;
  REP(i,n-1) {
    int a, b; cin >> a >> b;
    a--; b--;
    g[a].push_back(b);
    g[b].push_back(a);
  }
  int cnt = 0, cnt2 = 0, cnt3 = 0;
  int root = -1;
  REP(i,n) {
    if(g[i].size() == 1) cnt++;
    else if(g[i].size() == 2) cnt2++;
    else {
      root = i;
      cnt3++;
    }
  }

  if(cnt3 == 0) {
    cout << "Yes" << endl;
  }else if(cnt3 >= 2){
    cout << "No" << endl;
  }else{
  vector<int> dist(n, 1e9);
  dist[root] = 0;
  queue<int> q;
  q.push(root);
  while(q.size()) {
    int v = q.front();
    q.pop();
    for(auto u: g[v]) {
      if(dist[u] > dist[v] + 1) {
        dist[u] = dist[v] + 1;
        q.push(u);
      }
    }
  }
  map<int, int> mp;
  REP(i,n) {
    if(root != i && g[i].size() == 1) {
      mp[dist[i]]++;
    }
  }
  if(mp.size() == 1) cout << "Yes" << endl;
  else cout << "No" << endl;
  }
  return 0;
}
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