Submission #883770

#	Time	Username	Problem	Language	Result	Execution time	Memory
883770		noiaint	Alternating Heights (CCO22_day1problem1)	C++17	25 / 25	213 ms	42832 KiB

Main

#include <bits/stdc++.h>

using namespace std;

#ifdef LOCAL
#include "debug.h"
#else
#define debug(...) 42
#endif

#define file ""

#define mp make_pair
#define fi first
#define se second
#define all(x) x.begin(), x.end()

#define bit(x) (1LL << (x))
#define getbit(x, i) (((x) >> (i)) & 1)
#define popcount __builtin_popcountll

mt19937_64 rd(chrono::steady_clock::now().time_since_epoch().count());
int rand(int l, int r) {
    return l + rd() % (r - l + 1);
}

const int N = 1e6 + 5;
const int mod = (int)1e9 + 7; // 998244353;
const int lg = 25; // lg + 1
const int oo = 1e9;
const long long ooo = 1e18;

template<class X, class Y> bool mini(X &a, Y b) {
    return a > b ? (a = b, true) : false;
}
template<class X, class Y> bool maxi(X &a, Y b) {
    return a < b ? (a = b, true) : false;
}
void add(int &a, int b) {
    a += b;
    if (a >= mod) a -= mod;
    if (a < 0) a += mod;
}

int n, k, q;
int a[N];
vector<int> adj[N];
int color[N];
int res[N];

bool ok = true;

void dfs(int u) {
    color[u] = 1;
    for (int v : adj[u]) {
        if (!color[v]) dfs(v);
        else if (color[v] == 1) {
            ok = false;
            return;
        }
    }
    color[u] = 2;
}

bool no_cycle(int l, int r) {
    for (int i = 1; i <= k; ++i) {
        adj[i].clear();
        color[i] = 0;
    }

    vector<int> val;
    for (int i = l; i <= r; ++i) {
        if (i + 1 <= r && a[i] == a[i + 1]) return false;
        val.push_back(a[i]);
    }

    // edge x->y : x > y
    for (int i = 0; i + 1 < r - l + 1; ++i) {
        int x = val[i], y = val[i + 1];
        if (i & 1) adj[y].push_back(x);
        else adj[x].push_back(y);
    }

    for (int i = 1; i <= k; ++i) if (adj[i].size() && color[i] == 0) {
        ok = true;
        dfs(i);
        if (ok == false) return false;
    }
    return true;
}

void process() {
    cin >> n >> k >> q;
    for (int i = 1; i <= n; ++i) cin >> a[i];

    int r = 1;
    for (int l = 1; l <= n; ++l) {
        while (r <= n && no_cycle(l, r)) ++r;
        res[l] = r;
//        cout << res[l] << ' ';
    }

    while (q--) {
        int l, r;
        cin >> l >> r;
        cout << (res[l] > r ? "YES" : "NO") << '\n';
    }

}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);

    #ifdef LOCAL
    freopen("input.txt", "r", stdin);
    #else
    // freopen(file".inp", "r", stdin);
    // freopen(file".out", "w", stdout);
    #endif

    int tc = 1;
    // cin >> tc;

    while (tc--) {
        process();
    }

    return 0;
}

/*

*/

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