제출 #167933

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
167933		Thuleanx	새로운 문제 (POI11_roz)	C++14	0 / 100	751 ms	2512 KiB

roz

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

const int M = 26;
int n;
string s;

int best[M][M];
int invalid[M][M];
int update_local[M];
int update_global[M];

int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);

	cin>>n>>s;
	int ans = 0;

	for (int _ = 0; _ < 2; _++) {
		for (int i = 0; i < M; i++) {
			for (int j = 0; j < M; j++)
				best[i][j] = invalid[i][j] = -1e9;
			update_local[i] = update_global[i] = 0;
		}
		for (int i = 0; i < n; i++) {
			// [i][s[i]-'a']--
			update_global[s[i]-'a']--;
			// [s[i]-'a'][i]++
			update_local[s[i]-'a']++;

			for (int c = 0; c < M; c++) if (c != s[i]-'a') {
				// make things valid
				best[c][s[i]-'a'] = max(best[c][s[i]-'a'], invalid[c][s[i]-'a']);
				best[c][s[i]-'a'] = max(best[s[i]-'a'][c], -1-update_local[c] -update_global[s[i]-'a']);

				ans = max(ans, best[s[i]-'a'][c] + update_local[s[i]-'a'] + update_global[c]);

				// now new updates are invalid until activated
				invalid[s[i]-'a'][c] = max(invalid[s[i]-'a'][c], 1 - update_local[s[i]-'a'] - update_global[c]);
			}
		}
		reverse(begin(s), end(s));
	}


	cout << ans << endl;

	return 0;
}

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