Submission #866612

#	Time	Username	Problem	Language	Result	Execution time	Memory
866612		fanwen	Alternating Heights (CCO22_day1problem1)	C++17	25 / 25	196 ms	13940 KiB

Main

/**
 *      author : pham van sam 
 *      created : 26.10.2023 20:29:38
 **/

#include <bits/stdc++.h>

using namespace std;

#define MASK(x) (1LL << (x))
#define BIT(x, i) (((x) >> (i)) & 1)
#define ALL(x) (x).begin(), (x).end()
#define REP(i, n) for (int i = 0, _n = n; i < _n; ++i)
#define FOR(i, a, b) for (int i = (a), _b = (b); i <= _b; ++i)
#define FORD(i, a, b) for (int i = (a), _b = (b); i >= _b; --i)
#define FORE(i, a, b) for (int i = (a), _b = (b); i < _b; ++i)
#define debug(...) "[" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "] "
#define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }

template <class A, class B> bool minimize(A &a, B b)  { if (a > b) { a = b; return true; } return false; }
template <class A, class B> bool maximize(A &a, B b)  { if (a < b) { a = b; return true; } return false; }

const int MAXN = 3e3 + 5;

int N, K, Q, A[MAXN], res[MAXN], deg_in[MAXN], vis[MAXN], exist[MAXN];
vector <int> adj[MAXN];

void dfs(int u, int &ok) {
    vis[u] = 1;
    for (auto v : adj[u]) if(vis[v] < 2) {
        if(vis[v] == 1) {
            ok = 0;
            return;
        } else {
            dfs(v, ok);
        }
    }
    vis[u] = 2;
}

bool not_cycles(int l, int r) {
    fill(adj + 1, adj + K + 1, vector <int>());
    fill(deg_in + 1, deg_in + K + 1, 0);
    fill(vis + 1, vis + K + 1, 0);
    fill(exist + 1, exist + K + 1, 0);

    FOR(i, l, r) {
        exist[A[i]] = 1;
        if(i & 1) {
            if(i + 1 <= r) {
                adj[A[i]].push_back(A[i + 1]);
                deg_in[A[i + 1]]++;
            }
            if(i - 1 >= l) {
                adj[A[i]].push_back(A[i - 1]);
                deg_in[A[i - 1]]++;
            }
        } 
        // if(l == 2 && r == 4) {
        //     if(i % 2 == 1 && i + 1 <= r) {
        //         cout << A[i] << " " << A[i + 1] << '\n';
        //     }
        //     if(i % 2 == 0 && i - 1 >= l) {
        //         cout << A[i] << " " << A[i - 1] << '\n';
        //     }
        // }
    }

    FOR(i, 1, K) if(exist[i] && !deg_in[i]) {
        int oke = true;
        dfs(i, oke);
        if(!oke) return false;
    }

    FOR(i, 1, K) if(exist[i] && !vis[i]) return false;
    return true;
}

void you_make_it(void) {
    cin >> N >> K >> Q;
    FOR(i, 1, N) cin >> A[i];

    int j = 1;
    FOR(i, 1, N) {
        while(j <= N && not_cycles(i, j)) ++j;
        res[i] = j;
        // cout << res[i] << " \n"[i == N];
    }
    while(Q--) {
        int l, r; cin >> l >> r;
        cout << (res[l] <= r ? "NO\n" : "YES\n");
    }
}

signed main() {

#ifdef LOCAL
    freopen("TASK.inp", "r", stdin);
    freopen("TASK.out", "w", stdout);
#endif
    auto start_time = chrono::steady_clock::now();

    cin.tie(0), cout.tie(0) -> sync_with_stdio(0);

    you_make_it();

    auto end_time = chrono::steady_clock::now();

    cerr << "\nExecution time : " << chrono::duration_cast <chrono::milliseconds> (end_time - start_time).count() << "[ms]" << endl;

    return (0 ^ 0);
}

// Dream it. Wish it. Do it.

• Subtask 1: 4 / 4
• Subtask 2: 6 / 6
• Subtask 3: 7 / 7
• Subtask 4: 8 / 8