Submission #128154

#	Time	Username	Problem	Language	Result	Execution time	Memory
128154		ainta	AAQQZ (JOI15_aaqqz)	C++17	100 / 100	2832 ms	28172 KiB

aaqqz

#include<cstdio>
#include<algorithm>
#include<set>
using namespace std;
int n, K, w[3010], C[3010], S[3010], res, CC[3010], IT[3010], R[3010][3010];
void Do() {
	int i, j;
	for (i = 1; i <= n; i++) {
		for (j = n; j >= i; j--) {
			R[i][j] = 0;
			if (w[i - 1] == w[j + 1] && i > 1 && j < n)R[i][j] = R[i - 1][j + 1] + 1;
		}
	}
	for (i = 1; i < n; i++) {
		int b = i;
		for (j = 1; j <= K; j++)C[j] = 0;
		set<int>Set;
		C[w[b]]++;
		Set.insert(w[b]);
		while (b > 1 && w[b - 1] >= w[b]) {
			b--;
			C[w[b]]++;
			Set.insert(w[b]);
		}
		for (j = 1; j <= K; j++){
			S[j] = C[j];
			S[j] += S[j - 1];
		}
		int small = -1, smallc = 0;
		for (j = i + 1; j <= n; j++) {
			if (w[i] > w[j]) {
				if (small != -1) {
					if (small == w[j])smallc++;
					else break;
				}
				else {
					small = w[j]; smallc = 1;
				}
			}
			else {
				if (!C[w[j]])Set.insert(w[j]);
				C[w[j]]--;
				if (!C[w[j]])Set.erase(w[j]);
			}
			int last = K;
			if (!Set.empty()) last = *Set.begin();
			else{
				res = max(res, j - b + 1 + R[b][j] * 2);
			}
			res = max(res,S[last - 1] * 2 + (S[last] - S[last - 1] + min(0, -C[last]))*2 + smallc);
		}
	}
	for (i = 2; i <= n+n; i++) {
		int b = i / 2 + 1, e = i - i / 2 - 1;
		while (b > 1 && e < n && w[b - 1] == w[e + 1])b--, e++;
		int bb = b-1;
		for (j = 1; j <= K; j++)C[j] = 0;
		set<int>Set;
		res = max(res, e - b + 1);
		if (b == 1) continue;
		int be = bb;
		for (j = bb; j >= 1; j--) {
			if (j != bb && w[j] < w[j + 1])break;
			be = j;
			C[w[j]]++;
			Set.insert(w[j]);
		}
		for (j = 1; j <= K; j++) {
			S[j] = C[j];
			S[j] += S[j - 1];
		}
		for (j = e + 1; j <= n; j++) {
			if (w[bb] > w[j])break;
			if (!C[w[j]])Set.insert(w[j]);
			C[w[j]]--;
			if (!C[w[j]])Set.erase(w[j]);
			int last = K;
			if (!Set.empty()) last = *Set.begin();
			else {
				res = max(res, j - be + 1 + R[be][j] * 2);
			}
			res = max(res, S[last - 1] * 2 + (S[last] - S[last - 1] + min(0, -C[last]))*2 + e-b+1);
		}
	}
}
int Solve1() {
	int i;
	res = 0;
	for (i = 1; i <= K; i++)C[i] = 0;
	for (i = 1; i <= n; i++) {
		C[w[i]]++;
		res = max(res, C[w[i]]);
	}
	Do();
	reverse(w + 1, w + n + 1);
	for (i = 1; i <= n; i++)w[i] = K + 1 - w[i];
	Do();
	return res;
}
int main() {
	int i, j;
	scanf("%d%d", &n, &K);
	for (i = 1; i <= n; i++)scanf("%d", &w[i]);
	printf("%d\n", Solve1());
}

Compilation message (stderr)

aaqqz.cpp: In function 'int main()':
aaqqz.cpp:101:9: warning: unused variable 'j' [-Wunused-variable]
  int i, j;
         ^
aaqqz.cpp:102:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &n, &K);
  ~~~~~^~~~~~~~~~~~~~~~
aaqqz.cpp:103:31: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for (i = 1; i <= n; i++)scanf("%d", &w[i]);
                          ~~~~~^~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 90 / 90