Submission #74685087

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;

typedef unsigned long long ull;
typedef pair<ull, ull> puu;

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

	int N;
	cin >> N;
	vector<int> A(N);
	for (int i = 0; i < N; i++)
		cin >> A[i];

	const int MAX_LEN = 55;
	const ull B1 = 911382323;
	const ull B2 = 972663749;

	set<puu> found;

	for (int i = 0; i < N; i++) {
		ull h1 = 0, h2 = 0;
		int val = 0, len = 0;  // 当前块

		for (int j = i; j < min(i + MAX_LEN, N); j++) {
			h1 = h1 * B1 + A[j] + 1;
			h2 = h2 * B2 + A[j] + 1;

			if (len == 0) {
				// 第一个元素
				val = A[j];
				len = 1;
			} else if (val == A[j]) {
				// 同一块
				len++;
			} else {
				// 不同值，检查前一块
				if (len != val)
					break;  // 前一块不完整，无法形成221
				// 新块
				val = A[j];
				len = 1;
			}

			if (len > val)
				break;  // 当前块过长

			// 检查是否形成完整221序列
			if (len == val) {
				found.insert({h1, h2});
			}
		}
	}

	cout << found.size() << endl;

	return 0;
}

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