Submission #958515

#	Time	Username	Problem	Language	Result	Execution time	Memory
958515		MinaRagy06	Palindromes (APIO14_palindrome)	C++17	100 / 100	17 ms	36836 KiB

palindrome

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

const int N = 300'005;
struct node {
	int nxt[26];
	int par, len, suflink, cnt;
	node() {
		memset(nxt, 0, sizeof nxt);
		par = len = suflink = cnt = 0;
	}
} tree[N];
int nodes = 0, suf;
void build() {
	nodes++;
	tree[nodes].len = -1;
	tree[nodes].suflink = nodes;
	nodes++;
	tree[nodes].len = 0;
	tree[nodes].suflink = nodes - 1;
}
ll ans = 0;
int dfs(int i) {
	int cnt = tree[i].cnt;
	for (int j = 0; j < 26; j++) {
		if (!tree[i].nxt[j]) continue;
		cnt += dfs(tree[i].nxt[j]);
	}
	ans = max(ans, 1ll * cnt * tree[i].len);
	return cnt;
}
int main() {
	ios_base::sync_with_stdio(0), cin.tie(0);
	string s;
	cin >> s;
	int n = s.size();
	build();
	suf = 1;
	for (int i = 0; i < n; i++) {
		int cur = suf;
		while (i - tree[cur].len - 1 < 0 || s[i - tree[cur].len - 1] != s[i]) {
			cur = tree[cur].suflink;
		}
		bool old = 1;
		if (!tree[cur].nxt[s[i] - 'a']) {
			old = 0;
			nodes++;
			tree[cur].nxt[s[i] - 'a'] = nodes;
			tree[nodes].len = tree[cur].len + 2;
			tree[nodes].par = cur;
		}
		int p = tree[cur].nxt[s[i] - 'a'];
		tree[p].cnt++;
		suf = p;
		if (old) continue;
		if (tree[p].len == 1) {
			tree[p].suflink = 2;
			continue;
		}
		cur = tree[cur].suflink;
		while (i - tree[cur].len - 1 < 0 || s[i - tree[cur].len - 1] != s[i]) {
			cur = tree[cur].suflink;
		}
		cur = tree[cur].nxt[s[i] - 'a'];
		tree[p].suflink = cur;
	}
	for (int i = nodes; i >= 1; i--) {
// 		tree[tree[i].par].cnt += tree[i].cnt;
		tree[tree[i].suflink].cnt += tree[i].cnt;
// 		cout << i << ": " << tree[i].len << ' ' << tree[i].cnt << ' ' << tree[i].par << ' ' << tree[i].suflink << '\n';
		ans = max(ans, 1ll * tree[i].cnt * tree[i].len);
	}
	cout << ans << '\n';
	return 0;
}

• Subtask 1: 8 / 8
• Subtask 2: 15 / 15
• Subtask 3: 24 / 24
• Subtask 4: 26 / 26
• Subtask 5: 27 / 27