結果
| 問題 |
No.2403 "Eight" Bridges of Königsberg
|
| コンテスト | |
| ユーザー |
 poyon
|
| 提出日時 | 2023-08-04 22:27:42 |
| 言語 | C++17 (gcc 13.3.0 + boost 1.87.0) |
| 結果 |
AC
|
| 実行時間 | 42 ms / 2,000 ms |
| コード長 | 9,389 bytes |
| コンパイル時間 | 2,170 ms |
| コンパイル使用メモリ | 206,648 KB |
| 最終ジャッジ日時 | 2025-02-15 22:59:11 |
|
ジャッジサーバーID （参考情報） |
judge1 / judge5 |
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| ファイルパターン | 結果 |
|---|---|
| sample | AC * 4 |
| other | AC * 31 |
ソースコード
// clang-format off
#ifdef _LOCAL
#include <pch.hpp>
#else
#include <bits/stdc++.h>
#define cerr if (false) cerr
#define debug_bar
#define debug(...)
#define debug2(vv)
#define debug3(vvv)
#endif
using namespace std;
using ll = long long;
using ld = long double;
using str = string;
using P = pair<ll,ll>;
using VP = vector<P>;
using VVP = vector<VP>;
using VC = vector<char>;
using VS = vector<string>;
using VVS = vector<VS>;
using VI = vector<int>;
using VVI = vector<VI>;
using VVVI = vector<VVI>;
using VLL = vector<ll>;
using VVLL = vector<VLL>;
using VVVLL = vector<VVLL>;
using VB = vector<bool>;
using VVB = vector<VB>;
using VVVB = vector<VVB>;
using VD = vector<double>;
using VVD = vector<VD>;
using VVVD = vector<VVD>;
#define FOR(i,l,r) for (ll i = (l); i < (r); ++i)
#define RFOR(i,l,r) for (ll i = (r)-1; (l) <= i; --i)
#define REP(i,n) FOR(i,0,n)
#define RREP(i,n) RFOR(i,0,n)
#define FORE(e,c) for (auto&& e : c)
#define ALL(c) (c).begin(), (c).end()
#define SORT(c) sort(ALL(c))
#define RSORT(c) sort((c).rbegin(), (c).rend())
#define MIN(c) *min_element(ALL(c))
#define MAX(c) *max_element(ALL(c))
#define COUNT(c,v) count(ALL(c),(v))
#define len(c) ((ll)(c).size())
#define BIT(b,i) (((b)>>(i)) & 1)
#define PCNT(b) ((ll)__builtin_popcountll(b))
#define LB(c,v) distance((c).begin(), lower_bound(ALL(c), (v)))
#define UB(c,v) distance((c).begin(), upper_bound(ALL(c), (v)))
#define UQ(c) do { SORT(c); (c).erase(unique(ALL(c)), (c).end()); (c).shrink_to_fit(); } while (0)
#define END(...) do { print(__VA_ARGS__); exit(0); } while (0)
constexpr ld EPS = 1e-10;
constexpr ld PI = acosl(-1.0);
constexpr int inf = (1 << 30) - (1 << 15); // 1,073,709,056
constexpr ll INF = (1LL << 62) - (1LL << 31); // 4,611,686,016,279,904,256
template<class... T> void input(T&... a) { (cin >> ... >> a); }
void print() { cout << '\n'; }
template<class T> void print(const T& a) { cout << a << '\n'; }
template<class P1, class P2> void print(const pair<P1, P2>& a) { cout << a.first << " " << a.second << '\n'; }
template<class T, class... Ts> void print(const T& a, const Ts&... b) { cout << a; (cout << ... << (cout << ' ', b)); cout << '\n'; }
template<class T> void cout_line(const vector<T>& ans, int l, int r) { for (int i = l; i < r; i++) { if (i != l) { cout << ' '; } cout << ans[i]; } cout << '\n'; }
template<class T> void print(const vector<T>& a) { cout_line(a, 0, a.size()); }
template<class S, class T> bool chmin(S& a, const T b) { if (b < a) { a = b; return 1; } return 0; }
template<class S, class T> bool chmax(S& a, const T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> T SUM(const vector<T>& A) { return accumulate(ALL(A), T(0)); }
template<class T> vector<T> cumsum(const vector<T>& A, bool offset = false) { int N = A.size(); vector<T> S(N+1, 0); for (int i = 0; i < N; i++) { S[i+1] = S[i] + A[i]; } if (not offset) { S.erase(S.begin()); } return S; }
template<class T> string to_binary(T x, int B = 0) { string s; while (x) { s += ('0' + (x & 1)); x >>= 1; } while ((int)s.size() < B) { s += '0'; } reverse(s.begin(), s.end()); return s; }
template<class F> ll binary_search(const F& is_ok, ll ok, ll ng) { while (abs(ok - ng) > 1) { ll m = (ok + ng) / 2; (is_ok(m) ? ok : ng) = m; } return ok; }
template<class F> double binary_search_real(const F& is_ok, double ok, double ng, int iter = 90) { for (int i = 0; i < iter; i++) { double m = (ok + ng) / 2; (is_ok(m) ? ok : ng) = m; } return ok; }
template<class T> using PQ_max = priority_queue<T>;
template<class T> using PQ_min = priority_queue<T, vector<T>, greater<T>>;
template<class T> T pick(stack<T>& s) { assert(not s.empty()); T x = s.top(); s.pop(); return x; }
template<class T> T pick(queue<T>& q) { assert(not q.empty()); T x = q.front(); q.pop(); return x; }
template<class T> T pick_front(deque<T>& dq) { assert(not dq.empty()); T x = dq.front(); dq.pop_front(); return x; }
template<class T> T pick_back(deque<T>& dq) { assert(not dq.empty()); T x = dq.back(); dq.pop_back(); return x; }
template<class T> T pick(PQ_min<T>& pq) { assert(not pq.empty()); T x = pq.top(); pq.pop(); return x; }
template<class T> T pick(PQ_max<T>& pq) { assert(not pq.empty()); T x = pq.top(); pq.pop(); return x; }
template<class T> T pick(vector<T>& v) { assert(not v.empty()); T x = v.back(); v.pop_back(); return x; }
int to_int(const char c) { if (islower(c)) { return (c - 'a'); } if (isupper(c)) { return (c - 'A'); } if (isdigit(c)) { return (c - '0'); } assert(false); }
char to_a(const int i) { assert(0 <= i && i < 26); return ('a' + i); }
char to_A(const int i) { assert(0 <= i && i < 26); return ('A' + i); }
char to_d(const int i) { assert(0 <= i && i <= 9); return ('0' + i); }
ll min(int a, ll b) { return min((ll)a, b); }
ll min(ll a, int b) { return min(a, (ll)b); }
ll max(int a, ll b) { return max((ll)a, b); }
ll max(ll a, int b) { return max(a, (ll)b); }
ll mod(ll x, ll m) { assert(m > 0); return (x % m + m) % m; }
ll ceil(ll a, ll b) { if (b < 0) { return ceil(-a, -b); } assert(b > 0); return (a < 0 ? a / b : (a + b - 1) / b); }
ll floor(ll a, ll b) { if (b < 0) { return floor(-a, -b); } assert(b > 0); return (a > 0 ? a / b : (a - b + 1) / b); }
ll powint(ll x, ll n) { assert(n >= 0); if (n == 0) { return 1; }; ll res = powint(x, n>>1); res *= res; if (n & 1) { res *= x; } return res; }
pair<ll,ll> divmod(ll a, ll b) { assert(b != 0); ll q = floor(a, b); return make_pair(q, a - q * b); }
ll bitlen(ll b) { if (b <= 0) { return 0; } return (64LL - __builtin_clzll(b)); }
ll digitlen(ll n) { assert(n >= 0); if (n == 0) { return 1; } ll sum = 0; while (n > 0) { sum++; n /= 10; } return sum; }
ll msb(ll b) { return (b <= 0 ? -1 : (63 - __builtin_clzll(b))); }
ll lsb(ll b) { return (b <= 0 ? -1 : __builtin_ctzll(b)); }
// --------------------------------------------------------
// References:
// <https://github.com/atcoder/ac-library/blob/v1.4/atcoder/dsu.hpp>
// <https://en.wikipedia.org/wiki/Disjoint-set_data_structure>
// Disjoint-set data structure (Union Find)
//
struct dsu {
public:
dsu() : N(0) {}
explicit dsu(int n) : N(n), parent_or_size(n, -1), n_edge(n, 0) {}
// 辺 (a, b) を張ってマージ成否を返す : amortized O(α(N))
bool merge(int a, int b) {
assert(0 <= a && a < N);
assert(0 <= b && b < N);
int x = leader(a), y = leader(b);
if (x == y) { n_edge[x]++; return false; }
if (-parent_or_size[x] < -parent_or_size[y]) { swap(x, y); }
parent_or_size[x] += parent_or_size[y];
parent_or_size[y] = x;
n_edge[x] += n_edge[y] + 1;
return true;
}
// 頂点 a, b が連結か判定する : amortized O(α(N))
bool same(int a, int b) {
assert(0 <= a && a < N);
assert(0 <= b && b < N);
return leader(a) == leader(b);
}
// 頂点 a の属する連結成分のルートを返す : amortized O(α(N))
int leader(int a) {
assert(0 <= a && a < N);
if (parent_or_size[a] < 0) { return a; }
return parent_or_size[a] = leader(parent_or_size[a]);
}
// 頂点 a が属する連結成分のサイズを返す : amortized O(α(N))
int size(int a) {
assert(0 <= a && a < N);
return -parent_or_size[leader(a)];
}
// a が属する連結成分の辺の数を返す : amortized O(α(N))
int size_e(int a) {
assert(0 <= a && a < N);
return n_edge[leader(a)];
}
// 「一つの連結成分の頂点番号リスト」のリストを返す : O(N)
vector<vector<int>> groups() {
vector<int> leader_buf(N), group_size(N);
for (int i = 0; i < N; i++) {
leader_buf[i] = leader(i);
group_size[leader_buf[i]]++;
}
vector<vector<int>> result(N);
for (int i = 0; i < N; i++) {
result[i].reserve(group_size[i]);
}
for (int i = 0; i < N; i++) {
result[leader_buf[i]].push_back(i);
}
result.erase(
remove_if(result.begin(), result.end(),
[&](const vector<int>& v) { return v.empty(); }),
result.end());
return result;
}
private:
int N;
// [x < 0] -x が連結成分のサイズに対応
// [0 <= x] x が parent に対応
vector<int> parent_or_size;
vector<int> n_edge;
};
// clang-format on
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cout << fixed << setprecision(15);
int N, M;
cin >> N >> M;
VVI G(N);
VI deg(N);
dsu uf(N);
REP (_, M) {
int u, v;
cin >> u >> v;
u--;
v--;
G[u].push_back(v);
deg[u]--;
deg[v]++;
uf.merge(u, v);
}
if (N == 1) { END(0); }
if (SUM(deg) & 1) { END(-1); }
debug(deg);
ll L = 0, R = 0;
REP (u, N) {
if (deg[u] < 0) { L += deg[u]; }
if (deg[u] > 0) { R += deg[u]; }
}
ll C = 0;
ll D = 0;
FORE(g, uf.groups()) {
if (uf.size_e(g[0])) { C++; }
bool ok = false;
FORE(u, g) {
if (deg[u] != 0) { ok = true; }
}
D += ok;
}
ll ans = 0;
if (R == 0) {
ans = C - 1;
} else {
// ans = R - 1 + C - 1;
ans = R - 1 + C - D;
}
// ll ans = max({0ll, R - 1, C - 1});
print(ans);
return 0;
}