結果

問題 No.1865 Make Cycle
ユーザー haruki_Kharuki_K
提出日時 2022-05-06 01:11:50
言語 C++17
(gcc 12.3.0 + boost 1.83.0)
結果
AC  
実行時間 197 ms / 3,000 ms
コード長 8,519 bytes
コンパイル時間 2,322 ms
コンパイル使用メモリ 207,480 KB
実行使用メモリ 11,156 KB
最終ジャッジ日時 2023-09-18 11:30:07
合計ジャッジ時間 6,799 ms
ジャッジサーバーID
（参考情報） 		judge15 / judge14
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 137 ms
8,548 KB
testcase_01 AC 75 ms
6,800 KB
testcase_02 AC 154 ms
8,976 KB
testcase_03 AC 38 ms
7,672 KB
testcase_04 AC 92 ms
8,724 KB
testcase_05 AC 144 ms
9,216 KB
testcase_06 AC 134 ms
8,572 KB
testcase_07 AC 112 ms
8,068 KB
testcase_08 AC 142 ms
9,664 KB
testcase_09 AC 137 ms
9,204 KB
testcase_10 AC 142 ms
9,316 KB
testcase_11 AC 137 ms
9,156 KB
testcase_12 AC 108 ms
8,296 KB
testcase_13 AC 124 ms
8,084 KB
testcase_14 AC 90 ms
8,012 KB
testcase_15 AC 160 ms
9,196 KB
testcase_16 AC 163 ms
10,008 KB
testcase_17 AC 137 ms
8,000 KB
testcase_18 AC 141 ms
9,560 KB
testcase_19 AC 197 ms
11,156 KB
testcase_20 AC 1 ms
4,380 KB
testcase_21 AC 2 ms
4,380 KB
testcase_22 AC 1 ms
4,376 KB
testcase_23 AC 2 ms
4,380 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 # 

// >>> TEMPLATES
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using i32 = int32_t;
using i64 = int64_t;
using u32 = uint32_t;
using u64 = uint64_t;
#define int ll
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep1(i, n) for (int i = 1; i <= (int)(n); i++)
#define repR(i, n) for (int i = (int)(n)-1; i >= 0; i--)
#define rep1R(i, n) for (int i = (int)(n); i >= 1; i--)
#define loop(i, a, B) for (int i = a; i B; i++)
#define loopR(i, a, B) for (int i = a; i B; i--)
#define all(x) begin(x), end(x)
#define allR(x) rbegin(x), rend(x)
#define pb push_back
#define eb emplace_back
#define fst first
#define snd second
template <class Int> auto constexpr inf_ = numeric_limits<Int>::max()/2-1;
auto constexpr INF32 = inf_<int32_t>;
auto constexpr INF64 = inf_<int64_t>;
auto constexpr INF   = inf_<int>;
#ifdef LOCAL
#include "debug.hpp"
#define oj_local(x, y) (y)
#else
#define dump(...) (void)(0)
#define say(x) (void)(0)
#define debug if (0)
#define oj_local(x, y) (x)
#endif
template <class T, class Comp> struct pque : priority_queue<T, vector<T>, Comp> { vector<T> &data() { return this->c; } void clear() { this->c.clear(); } };
template <class T> using pque_max = pque<T, less<T>>;
template <class T> using pque_min = pque<T, greater<T>>;
template <class T, class = typename T::iterator, enable_if_t<!is_same<T, string>::value, int> = 0>
ostream& operator<<(ostream& os, T const& a) { bool f = true; for (auto const& x : a) os << (f ? "" : " ") << x, f = false; return os; }
template <class T, size_t N, enable_if_t<!is_same<T, char>::value, int> = 0>
ostream& operator<<(ostream& os, const T (&a)[N]) { bool f = true; for (auto const& x : a) os << (f ? "" : " ") << x, f = false; return os; }
template <class T, class = decltype(begin(declval<T&>())), class = typename enable_if<!is_same<T, string>::value>::type>
istream& operator>>(istream& is, T &a) { for (auto& x : a) is >> x; return is; }
template <class T, class S> ostream& operator<<(ostream& os, pair<T, S> const& p) { return os << p.first << " " << p.second; }
template <class T, class S> istream& operator>>(istream& is, pair<T, S>& p) { return is >> p.first >> p.second; }
struct IOSetup { IOSetup() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(15); } } iosetup;
template <class F> struct FixPoint : private F {
    constexpr FixPoint(F&& f) : F(forward<F>(f)) {}
    template <class... T> constexpr auto operator()(T&&... x) const { return F::operator()(*this, forward<T>(x)...); }
};
struct MakeFixPoint { template <class F> constexpr auto operator|(F&& f) const { return FixPoint<F>(forward<F>(f)); } };
#define MFP MakeFixPoint()|
#define def(name, ...) auto name = MFP [&](auto &&name, __VA_ARGS__)
template <class T, size_t d> struct vec_impl {
    using type = vector<typename vec_impl<T, d-1>::type>;
    template <class... U> static type make_v(size_t n, U&&... x) { return type(n, vec_impl<T, d-1>::make_v(forward<U>(x)...)); }
};
template <class T> struct vec_impl<T, 0> { using type = T; static type make_v(T const& x = {}) { return x; } };
template <class T, size_t d = 1> using vec = typename vec_impl<T, d>::type;
template <class T, size_t d = 1, class... Args> auto make_v(Args&&... args) { return vec_impl<T, d>::make_v(forward<Args>(args)...); }
template <class T> void quit(T const& x) { cout << x << endl; exit(0); }
template <class T, class U> constexpr bool chmin(T& x, U const& y) { if (x > (T)y) { x = (T)y; return true; } return false; }
template <class T, class U> constexpr bool chmax(T& x, U const& y) { if (x < (T)y) { x = (T)y; return true; } return false; }
template <class It> constexpr auto sumof(It b, It e) { return accumulate(b, e, typename iterator_traits<It>::value_type{}); }
template <class T> int sz(T const& x) { return x.size(); }
template <class C, class T> int lbd(C const& v, T const& x) { return lower_bound(begin(v), end(v), x)-begin(v); }
template <class C, class T> int ubd(C const& v, T const& x) { return upper_bound(begin(v), end(v), x)-begin(v); }
constexpr ll mod(ll x, ll m) { assert(m > 0); return (x %= m) < 0 ? x+m : x; }
constexpr ll div_floor(ll x, ll y) { assert(y != 0); return x/y - ((x^y) < 0 and x%y); }
constexpr ll div_ceil(ll x, ll y) { assert(y != 0); return x/y + ((x^y) > 0 and x%y); }
constexpr int dx[] = { 1, 0, -1, 0, 1, -1, -1, 1 };
constexpr int dy[] = { 0, 1, 0, -1, 1, 1, -1, -1 };
constexpr int popcnt(ll x) { return __builtin_popcountll(x); }
mt19937_64 seed_{random_device{}()};
template <class Int> Int rand(Int a, Int b) { return uniform_int_distribution<Int>(a, b)(seed_); }
i64 irand(i64 a, i64 b) { return rand<i64>(a, b); } // [a, b]
u64 urand(u64 a, u64 b) { return rand<u64>(a, b); } //
template <class It> void shuffle(It l, It r) { shuffle(l, r, seed_); }
template <class V> V &operator--(V &v) { for (auto &x : v) --x; return v; }
template <class V> V &operator++(V &v) { for (auto &x : v) ++x; return v; }
bool next_product(vector<int> &v, int m) {
    repR (i, v.size()) if (++v[i] < m) return true; else v[i] = 0;
    return false;
}
bool next_product(vector<int> &v, vector<int> const& s) {
    repR (i, v.size()) if (++v[i] < s[i]) return true; else v[i] = 0;
    return false;
}
template <class vec> int sort_unique(vec &v) {
    sort(begin(v), end(v));
    v.erase(unique(begin(v), end(v)), end(v));
    return v.size();
}
template <class It> auto prefix_sum(It l, It r) {
    vector<typename It::value_type> s = { 0 };
    while (l != r) s.emplace_back(s.back() + *l++);
    return s;
}
template <class It> auto suffix_sum(It l, It r) {
    vector<typename It::value_type> s = { 0 };
    while (l != r) s.emplace_back(*--r + s.back());
    reverse(s.begin(), s.end());
    return s;
}
template <class T> T pop(vector<T> &a) { auto x = a.back(); a.pop_back(); return x; }
template <class T, class V, class C> T pop(priority_queue<T, V, C> &a) { auto x = a.top(); a.pop(); return x; }
template <class T> T pop(queue<T> &a) { auto x = a.front(); a.pop(); return x; }
template <class T> T pop_front(deque<T> &a) { auto x = a.front(); a.pop_front(); return x; }
template <class T> T pop_back(deque<T> &a) { auto x = a.back(); a.pop_back(); return x; }
template <class T> T pop_front(set<T> &a) { auto x = *a.begin(); a.erase(a.begin()); return x; }
template <class T> T pop_back(set<T> &a) { auto it = prev(a.end()); auto x = *it; a.erase(it); return x; }
template <class T> T pop_front(multiset<T> &a) { auto it = a.begin(); auto x = *it; a.erase(it); return x; }
template <class T> T pop_back(multiset<T> &a) { auto it = prev(a.end()); auto x = *it; a.erase(it); return x; }
// <<<
// >>> find cycle (directed graph)
#ifndef EDGE_INFO
#define EDGE_INFO
constexpr int dest(int v) { return v; }
template <class E, class = decltype(declval<E>().to)>
constexpr int dest(E const& e) { return e.to; }
constexpr int cost(int) { return 1; }
template <class E, class = decltype(declval<E>().cost)>
constexpr auto cost(E const& e) { return e.cost; }
template <class E> using cost_t = decltype(cost(declval<E>()));
#endif
// returns empty if not found
template <class E>
vector<E> find_cycle(vector<vector<E>> const& g) {
    const int n = g.size();
    vector<int> in(n, -1), out(n, -1);
    vector<E> path, cycle;
    int time = 0;
    auto dfs = [&](auto dfs, int x) -> bool {
        in[x] = time++;
        for (auto const& e : g[x]) {
            const int y = dest(e);
            if (in[y] < 0) {
                path.push_back(e);
                if (dfs(dfs, y)) return true;
                path.pop_back();
            } else if (out[y] < 0) {
                cycle.push_back(e);
                while (path.size() and dest(path.back()) != y) {
                    cycle.push_back(path.back());
                    path.pop_back();
                }
                reverse(cycle.begin(), cycle.end());
                return true;
            }
        }
        out[x] = time;
        return false;
    };
    rep (x, n) if (in[x] < 0 and dfs(dfs, x)) return cycle;
    return {};
}
// <<<

int32_t main() {
    int n, q; cin >> n >> q;
    vector<int> a, b;
    rep (i, q) {
        int x, y; cin >> x >> y; --x, --y;
        a.eb(x);
        b.eb(y);
    }

    int l = 0, r = q+1;
    while (l+1 < r) {
        auto m = (l+r)/2;

        vector<vector<int>> g(n);
        rep (i, m) g[a[i]].eb(b[i]);
        (find_cycle(g).empty() ? l : r) = m;
    }

    if (r == q+1) {
        cout << -1 << '\n';
    } else {
        cout << r << '\n';
    }

}
0