Submission #1288228

#	Time	Username	Problem	Language	Result	Execution time	Memory
1288228		mingga	Sequence (APIO23_sequence)	C++20	50 / 100	2098 ms	78696 KiB

sequence

#include "bits/stdc++.h"

using namespace std;

#define ln "\n"
#define pb push_back
#define fi first
#define se second
#define all(x) (x).begin(), (x).end()
#define sz(x) ((int)(x).size())
#define ll long long
const int mod = 1e9 + 7;
const int inf = 2e9;
const int N = 5e5 + 7;

vector<int> pos[N];

struct SEGTREE {
	vector<pair<int, int>> st;
	vector<int> lazy;
	int n;
	SEGTREE(int n) : n(n) {
		st.resize(n * 4 + 4, {0, 0});
		lazy.resize(n * 4 + 4, 0);
		init();
	}	

	pair<int, int> merge(pair<int, int> X, pair<int, int> Y) {
		return make_pair(min(X.fi, Y.fi), max(X.se, Y.se));
	}
	void build(int i, int l, int r) {
		if(l == r) {
			st[i] = {-l, -l};
			return;
		}
		int m = (l + r) >> 1;
		build(i * 2, l, m);
		build(i * 2 + 1, m + 1, r);
		st[i] = merge(st[i * 2], st[i * 2 + 1]); 
	}

	void push(int i) {
		if(lazy[i]) {
			int x = lazy[i];
			lazy[i] = 0;
			for(int j = 2 * i; j <= 2 * i + 1; j++) {
				st[j].fi += x, st[j].se += x;
				lazy[j] += x;
			}
		}
	}
	void update(int i, int l, int r, int u, int v, int x) {
		if(l > v or r < u) return;
		if(u <= l and r <= v) {
			st[i].fi += x;
			st[i].se += x;
			lazy[i] += x;
			return;
		}
		int m = (l + r) >> 1;
		push(i);
		update(i * 2, l, m, u, v, x);
		update(i * 2 + 1, m + 1, r, u, v, x);
		st[i] = merge(st[i * 2], st[i * 2 + 1]);
	}
	pair<int, int> get(int i, int l, int r, int u, int v) {
		if(l > v or r < u) return {inf, -inf};
		if(u <= l and r <= v) return st[i];
		int m = (l + r) >> 1;
		push(i);
		return merge(get(i * 2, l, m, u, v), get(i * 2 + 1, m + 1, r, u, v));
	}
	void init() {
		build(1, 0, n);
	}
	void update(int l, int r, int x) {
		update(1, 0, n, l, r, x);
	}
	pair<int, int> get(int l, int r) {
		return get(1, 0, n, l, r);
	} 
};

bool check(int mid, int n) {
	SEGTREE st(n), pre(n);
	for(int i = 1; i <= n; i++) {
		for(int x : pos[i]) {
			st.update(x, n, 2);
		}
		if(sz(pos[i]) >= mid) {
			for(int j = mid - 1; j < sz(pos[i]); j++) {
				int r = pos[i][j], l = pos[i][j - mid + 1];
				pair<int, int> sus1 = pre.get(0, l - 1), sus2 = pre.get(r, n);
				pair<int, int> dak1 = st.get(0, l - 1), dak2 = st.get(r, n);
				int mn1 = sus2.fi - sus1.se;
				int mx2 = dak2.se - dak1.fi;
				if(mn1 <= 0 and mx2 >= 0) {
					return 1;
				}
			}
		}
		for(int x : pos[i]) {
			pre.update(x, n, 2);
		}
	}
	return 0;
}

int sequence(int n, vector<int> a) {
	for(int i = 0; i < n; i++) {
		pos[a[i]].pb(i + 1);
	}
	int l = 1, r = n;
	int ans = 1;
	while(l <= r) {
		int mid = (l + r) >> 1;
		if(check(mid, n)) {
			ans = mid;
			l = mid + 1;
		} else r = mid - 1;
	}
	return ans;
}

// signed main() {
// 	cin.tie(0) -> sync_with_stdio(0);
// 	int n; cin >> n;
// 	vector<int> a;
// 	for(int i = 1; i <= n; i++) {
// 		int x; cin >> x;
// 		a.pb(x); 
// 	}
// 	cout << sequence(n, a) << ln;
// }

• Subtask 1: 11 / 11
• Subtask 2: 17 / 17
• Subtask 3: 0 / 7
• Subtask 4: 0 / 12
• Subtask 5: 0 / 13
• Subtask 6: 22 / 22
• Subtask 7: 0 / 18