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Submission #648709

# Submission time Handle Problem Language Result Execution time Memory
648709 2022-10-07T14:41:06 Z ymm Palindromes (APIO14_palindrome) C++17
100 / 100
 120 ms 73916 KB 
#include <bits/stdc++.h>
#define Loop(x,l,r) for (ll x = (l); x < (ll)(r); ++x)
#define LoopR(x,l,r) for (ll x = (r)-1; x >= (ll)(l); --x)
typedef long long ll;
typedef std::pair<int, int> pii;
typedef std::pair<ll , ll > pll;
using namespace std;

const int N = 300'010;
const int alpha = 26;
int longest_palin[N];
int second_longest[N];
string s;
int n;

struct node {
	int link = 0;
	int next[alpha] = {};
	int len = 0;
	int cnt = 0;
	bool vis = 0;
} pool[10000000];

int rt = 1;

int make_node()
{
	static int nxt = 2;
	return nxt++;
}

int lst_node = rt;
vector<int> all_nodes = {rt};
void insert_node(char c)
{
	c -= 'a';
	int new_node = make_node();
	all_nodes.push_back(new_node);
	pool[new_node].cnt = 1;
	pool[new_node].len = pool[lst_node].len + 1;
	int cur = lst_node;
	lst_node = new_node;
	while (cur) {
		if (!pool[cur].next[c]) {
			pool[cur].next[c] = new_node;
			cur = pool[cur].link;
		} else {
			break;
		}
	}
	if (!cur) {
		pool[new_node].link = rt;
		return;
	}
	int q = pool[cur].next[c];
	if (pool[cur].len + 1 == pool[q].len) {
		pool[new_node].link = q;
		return;
	}
	int clone = make_node();
	all_nodes.push_back(clone);
	pool[clone] = pool[q];
	pool[clone].cnt = 0;
	pool[clone].len = pool[cur].len + 1;
	pool[q].link = clone;
	while (cur && pool[cur].next[c] == q) {
		pool[cur].next[c] = clone;
		cur = pool[cur].link;
	}
	pool[new_node].link = clone;
}

int index2node[N];

void make_automata()
{
	Loop (i,0,n) {
		insert_node(s[i]);
		index2node[i] = lst_node;
	}
	sort(all_nodes.begin(), all_nodes.end(), [](int a, int b) {
		return pool[a].len < pool[b].len;
	});
	LoopR (i,1,all_nodes.size()) {
		int t = all_nodes[i];
		pool[pool[t].link].cnt += pool[t].cnt;
	}
}

void find_palin(int i)
{
	int j = i-1;
	while (longest_palin[j] == i || s[i-longest_palin[j]-1] != s[i]) {
		if (second_longest[j] == -1) {
			if (s[i] == s[i-1]) {
				longest_palin[i] = 2;
				second_longest[i] = j;
			} else {
				longest_palin[i] = 1;
				second_longest[i] = -1;
			}
			return;
		}
		j = second_longest[j];
	}
	longest_palin[i] = longest_palin[j]+2;
	int sec_len = -1;
	do {
		if (second_longest[j] == -1) {
			sec_len = 1 + (s[i] == s[j]);
			break;
		}
		j = second_longest[j];
	} while (longest_palin[j] == i || s[i-longest_palin[j]-1] != s[i]);
	if (sec_len == -1)
		sec_len = longest_palin[j] + 2;
	j = i - longest_palin[i] + sec_len;
	while (longest_palin[j] != sec_len)
		j = second_longest[j];
	second_longest[i] = j;
}

void find_all_palins()
{
	longest_palin[0] = 1;
	second_longest[0] = -1;
	Loop (i,1,n)
		find_palin(i);
}

int main()
{
	cin.tie(0) -> sync_with_stdio(false);
	cin >> s;
	n = s.size();
	make_automata();
	find_all_palins();
	ll ans = 0;
	Loop (i,0,n) {
		int t = index2node[i];
		while (pool[pool[t].link].len >= longest_palin[i]) {
			pool[t].vis = 1;
			t = pool[t].link;
			if (pool[t].vis)
				break;
		}
		if (pool[t].vis)
			continue;
		ans = max(ans, (ll)longest_palin[i] * pool[t].cnt);
	}
	cout << ans << '\n';
}

Compilation message

palindrome.cpp: In function 'void insert_node(char)':
palindrome.cpp:44:23: warning: array subscript has type 'char' [-Wchar-subscripts]
   44 |   if (!pool[cur].next[c]) {
      |                       ^
palindrome.cpp:45:19: warning: array subscript has type 'char' [-Wchar-subscripts]
   45 |    pool[cur].next[c] = new_node;
      |                   ^
palindrome.cpp:55:25: warning: array subscript has type 'char' [-Wchar-subscripts]
   55 |  int q = pool[cur].next[c];
      |                         ^
palindrome.cpp:66:31: warning: array subscript has type 'char' [-Wchar-subscripts]
   66 |  while (cur && pool[cur].next[c] == q) {
      |                               ^
palindrome.cpp:67:18: warning: array subscript has type 'char' [-Wchar-subscripts]
   67 |   pool[cur].next[c] = clone;
      |                  ^

Subtask #1
8.0 / 8.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 340 KB Output is correct
2 Correct 1 ms 340 KB Output is correct
3 Correct 1 ms 340 KB Output is correct
4 Correct 0 ms 340 KB Output is correct
5 Correct 0 ms 340 KB Output is correct
6 Correct 0 ms 344 KB Output is correct
7 Correct 1 ms 340 KB Output is correct
8 Correct 1 ms 468 KB Output is correct
9 Correct 1 ms 348 KB Output is correct
10 Correct 1 ms 348 KB Output is correct
11 Correct 1 ms 340 KB Output is correct
12 Correct 0 ms 340 KB Output is correct
13 Correct 1 ms 340 KB Output is correct
14 Correct 1 ms 340 KB Output is correct
15 Correct 1 ms 344 KB Output is correct
16 Correct 1 ms 348 KB Output is correct
17 Correct 1 ms 340 KB Output is correct
18 Correct 1 ms 348 KB Output is correct
19 Correct 1 ms 340 KB Output is correct
20 Correct 1 ms 340 KB Output is correct
21 Correct 1 ms 340 KB Output is correct
22 Correct 1 ms 340 KB Output is correct
23 Correct 1 ms 340 KB Output is correct
24 Correct 1 ms 344 KB Output is correct
25 Correct 1 ms 340 KB Output is correct
26 Correct 1 ms 340 KB Output is correct
27 Correct 1 ms 340 KB Output is correct
28 Correct 1 ms 348 KB Output is correct
29 Correct 1 ms 348 KB Output is correct
30 Correct 0 ms 340 KB Output is correct
31 Correct 1 ms 340 KB Output is correct
32 Correct 1 ms 340 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 480 KB Output is correct
2 Correct 1 ms 468 KB Output is correct
3 Correct 1 ms 476 KB Output is correct
4 Correct 1 ms 468 KB Output is correct
5 Correct 1 ms 468 KB Output is correct
6 Correct 1 ms 468 KB Output is correct
7 Correct 1 ms 468 KB Output is correct
8 Correct 1 ms 468 KB Output is correct
9 Correct 1 ms 596 KB Output is correct
10 Correct 1 ms 468 KB Output is correct
11 Correct 1 ms 472 KB Output is correct
12 Correct 1 ms 468 KB Output is correct

Subtask #3
24.0 / 24.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 1748 KB Output is correct
2 Correct 3 ms 2692 KB Output is correct
3 Correct 2 ms 1756 KB Output is correct
4 Correct 3 ms 2772 KB Output is correct
5 Correct 2 ms 1760 KB Output is correct
6 Correct 3 ms 2580 KB Output is correct
7 Correct 3 ms 3028 KB Output is correct
8 Correct 2 ms 2004 KB Output is correct
9 Correct 2 ms 2020 KB Output is correct
10 Correct 3 ms 2260 KB Output is correct

Subtask #4
26.0 / 26.0

# Verdict Execution time Memory Grader output
1 Correct 14 ms 13996 KB Output is correct
2 Correct 31 ms 19272 KB Output is correct
3 Correct 14 ms 14088 KB Output is correct
4 Correct 31 ms 18368 KB Output is correct
5 Correct 15 ms 14096 KB Output is correct
6 Correct 27 ms 18692 KB Output is correct
7 Correct 36 ms 23424 KB Output is correct
8 Correct 36 ms 17416 KB Output is correct
9 Correct 32 ms 19464 KB Output is correct
10 Correct 33 ms 20228 KB Output is correct

Subtask #5
27.0 / 27.0

# Verdict Execution time Memory Grader output
1 Correct 52 ms 40988 KB Output is correct
2 Correct 111 ms 72692 KB Output is correct
3 Correct 45 ms 41064 KB Output is correct
4 Correct 115 ms 65096 KB Output is correct
5 Correct 55 ms 41060 KB Output is correct
6 Correct 102 ms 67528 KB Output is correct
7 Correct 120 ms 73916 KB Output is correct
8 Correct 120 ms 51332 KB Output is correct
9 Correct 113 ms 51320 KB Output is correct
10 Correct 95 ms 57032 KB Output is correct
11 Correct 45 ms 41008 KB Output is correct
12 Correct 113 ms 53404 KB Output is correct