結果

問題 No.1424 Ultrapalindrome
コンテスト
ユーザー minato
提出日時 2021-03-13 19:22:25
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 45 ms / 2,000 ms
コード長 5,871 bytes
コンパイル時間 2,170 ms
コンパイル使用メモリ 203,124 KB
最終ジャッジ日時 2025-01-19 16:12:28
ジャッジサーバーID
（参考情報） 		judge2 / judge4
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 3
other AC * 29
権限があれば一括ダウンロードができます
コンパイルメッセージ
main.cpp: In function ‘int main()’:
main.cpp:105:25: warning: ‘m’ may be used uninitialized [-Wmaybe-uninitialized]
  105 |     auto dist2 = bfs(G,m);
      |                         ^
main.cpp:97:9: note: ‘m’ was declared here
   97 |     int m;
      |         ^

ソースコード

diff # 

#include <bits/stdc++.h>
using namespace std;
using uint = unsigned int;
using ll = long long;
using ull = unsigned long long;
using pii = pair<int, int>;
using pll = pair<long long, long long>;
template <class T> using vec = vector<T>;
template <class T> using vvec = vector<vector<T>>;
#define rep(i, n) for (int i = 0; i < (n); i++)
#define rrep(i, n) for (int i = int(n) - 1; i >= 0; i--)
#define all(x) begin(x), end(x)
constexpr char ln = '\n';
template <class Container> inline int SZ(const Container& v) { return int(v.size()); }
template <class T> inline void UNIQUE(vector<T>& v) { v.erase(unique(v.begin(), v.end()), v.end()); }
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; }
inline int topbit(ull x) { return x == 0 ? -1 : 63 - __builtin_clzll(x); }
inline int botbit(ull x) { return x == 0 ? 64 : __builtin_ctzll(x); }
inline int popcount(ull x) { return __builtin_popcountll(x); }
inline int kthbit(ull x, int k) { return (x >> k) & 1; }
inline constexpr long long TEN(int x) { return x == 0 ? 1 : TEN(x - 1) * 10; }
const string YESNO[2] = {"NO", "YES"};
const string YesNo[2] = {"No", "Yes"};
inline void YES(bool t = true) { cout << YESNO[t] << "\n"; }
inline void Yes(bool t = true) { cout << YesNo[t] << "\n"; }
template <class T> inline void drop(T x) { cout << x << "\n"; exit(0); }
inline void print() { cout << "\n"; }
template <class T> inline void print(const vector<T>& v) { for (auto it = v.begin(); it != v.end(); ++it) { if (it != v.begin()) { cout << " "; } cout << *it; } print(); }
template <class T, class... Args> inline void print(const T& x, const Args& ... args) { cout << x << " "; print(args...); }
#ifdef MINATO_LOCAL
template <class T1, class T2> ostream& operator<<(ostream& os, pair<T1, T2> p) { return os << "(" << p.first << ", " << p.second << ")"; }
template <size_t N, class TUPLE> void debug_tuple(ostream& os, TUPLE _) { (void)os; (void)_; }
template <size_t N, class TUPLE, class T, class ...Args> void debug_tuple(ostream &os, TUPLE t) { os << (N == 0 ? "" : ", ") << get<N>(t); debug_tuple<N + 1, TUPLE, Args...>(os, t); }
template <class ...Args> ostream& operator<<(ostream& os, tuple<Args...> t) { os << "("; debug_tuple<0, tuple<Args...>, Args...>(os, t); return os << ")"; }
string debug_delim(int& i) { return i++ == 0 ? "" : ", "; }
#define debug_embrace(x) { int i = 0; os << "{";  { x } return os << "}"; }
template <class T> ostream& operator<<(ostream& os, vector<T> v) { debug_embrace( for (T e : v) { os << debug_delim(i) << e; } ) }
template <class T, size_t N> ostream& operator<<(ostream& os, array<T, N> a) { debug_embrace( for (T e : a) { os << debug_delim(i) << e; } ) }
template <class T, size_t N> enable_if_t<!is_same_v<char, remove_cv_t<T>>, ostream>& operator<<(ostream& os, T(&a)[N]) { debug_embrace( for (T e : a) { os << debug_delim(i) << e; } ) }
template <class Key> ostream& operator<<(ostream& os, set<Key> s) { debug_embrace( for (Key e : s) { os << debug_delim(i) << e; }) }
template <class Key, class T> ostream& operator<<(ostream& os, map<Key, T> mp) { debug_embrace( for (auto e : mp) { os << debug_delim(i) << e; }) }
template <class Key> ostream& operator<<(ostream& os, multiset<Key> s) { debug_embrace( for (Key e : s) { os << debug_delim(i) << e; }) }
template <class T> ostream& operator<<(ostream& os, queue<T> q) { debug_embrace( for (; !q.empty(); q.pop()) { os << debug_delim(i) << q.front(); } ) }
template <class T> ostream& operator<<(ostream& os, deque<T> q) { debug_embrace( for (T e : q) { os << debug_delim(i) << e; } ) }
template <class T> ostream& operator<<(ostream& os, priority_queue<T> q) { debug_embrace( for (; !q.empty(); q.pop()) { os << debug_delim(i) << q.top(); } ) }
template <class T> ostream& operator<<(ostream& os, priority_queue<T, vector<T>, greater<T>> q) { debug_embrace( for (; !q.empty(); q.pop()) { os << debug_delim(i) << q.top(); } ) }
void debug_out() { cerr << endl; }
template <class T, class... Args> void debug_out(const T& x, const Args& ... args) { cerr << " " << x; debug_out(args...); }
#define debug(...) cerr << __LINE__ << " : [" << #__VA_ARGS__ << "] =", debug_out(__VA_ARGS__)
#else
#define debug(...) (void(0))
#endif
struct fast_ios { fast_ios() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(20); cerr << fixed << setprecision(7); }; } fast_ios_;
///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

vector<int> bfs(const vector<vector<int>>& G, int s = 0) {
    vector<int> ret(G.size(), -1);
    ret[s] = 0;
    queue<int> que;
    que.emplace(s);
    while (!que.empty()) {
        int v = que.front(); que.pop();
        for (int nv : G[v]) {
            if (~ret[nv]) continue;
            ret[nv] = ret[v] + 1;
            que.emplace(nv);
        }
    }
    return ret;
}

int main() {
    int N; cin >> N;
    vec<int> deg(N);
    vvec<int> G(N);
    rep(i,N-1) {
        int a,b; cin >> a >> b;
        a--; b--;
        G[a].emplace_back(b);
        G[b].emplace_back(a);
        deg[a]++;
        deg[b]++;
    }

    vec<int> ls;
    rep(i,N) {
        if (deg[i]==1) ls.emplace_back(i);
    }

    auto dist = bfs(G,ls[0]);
    int D = *max_element(all(dist));
    if (D&1) {
        Yes(SZ(ls)==2);
        return 0;
    }
    int m;
    rep(i,N) {
        if (D/2==dist[i]) {
            m = i;
            break;
        }
    }

    auto dist2 = bfs(G,m);
    rep(i,N) {
        if (i==m) continue;
        if (deg[i]==1) {
            if (dist2[i]!=D/2) drop("No");
        } else {
            if (deg[i]!=2) drop("No");
        }
    }
    Yes(1);
}
0