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Submission #648697

# Submission time Handle Problem Language Result Execution time Memory
648697 2022-10-07T13:47:32 Z ymm Palindromes (APIO14_palindrome) C++17
100 / 100
 148 ms 73900 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]) {
			longest_palin[i] = 1 + (s[i] == s[i-1]);
			second_longest[i] = s[i] == s[i-1];
			return;
		}
		int k = second_longest[j];
		while(longest_palin[j] != k)
			j = j-longest_palin[j]+second_longest[j];
	}
	longest_palin[i] = longest_palin[j]+2;
	do {
		if (!second_longest[j]) {
			second_longest[i] = 1 + (s[i] == s[i-1]);
			return;
		}
		int k = second_longest[j];
		while(longest_palin[j] != k)
			j = j-longest_palin[j]+second_longest[j];
	} while (longest_palin[j] == i || s[i-longest_palin[j]-1] != s[i]);
	second_longest[i] = longest_palin[j]+2;
}

void find_all_palins()
{
	longest_palin[0] = 1;
	second_longest[0] = 0;
	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 0 ms 340 KB Output is correct
2 Correct 0 ms 340 KB Output is correct
3 Correct 0 ms 340 KB Output is correct
4 Correct 1 ms 340 KB Output is correct
5 Correct 0 ms 340 KB Output is correct
6 Correct 1 ms 340 KB Output is correct
7 Correct 0 ms 340 KB Output is correct
8 Correct 0 ms 340 KB Output is correct
9 Correct 0 ms 340 KB Output is correct
10 Correct 1 ms 340 KB Output is correct
11 Correct 0 ms 340 KB Output is correct
12 Correct 0 ms 340 KB Output is correct
13 Correct 0 ms 340 KB Output is correct
14 Correct 0 ms 340 KB Output is correct
15 Correct 0 ms 340 KB Output is correct
16 Correct 0 ms 340 KB Output is correct
17 Correct 1 ms 340 KB Output is correct
18 Correct 1 ms 340 KB Output is correct
19 Correct 0 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 384 KB Output is correct
23 Correct 1 ms 296 KB Output is correct
24 Correct 1 ms 340 KB Output is correct
25 Correct 0 ms 340 KB Output is correct
26 Correct 0 ms 340 KB Output is correct
27 Correct 1 ms 340 KB Output is correct
28 Correct 0 ms 340 KB Output is correct
29 Correct 1 ms 340 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 468 KB Output is correct
2 Correct 1 ms 468 KB Output is correct
3 Correct 1 ms 468 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 468 KB Output is correct
10 Correct 1 ms 468 KB Output is correct
11 Correct 1 ms 468 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 1 ms 1748 KB Output is correct
2 Correct 3 ms 2772 KB Output is correct
3 Correct 2 ms 1748 KB Output is correct
4 Correct 3 ms 2772 KB Output is correct
5 Correct 2 ms 1748 KB Output is correct
6 Correct 3 ms 2560 KB Output is correct
7 Correct 4 ms 2928 KB Output is correct
8 Correct 2 ms 2004 KB Output is correct
9 Correct 3 ms 2004 KB Output is correct
10 Correct 2 ms 2132 KB Output is correct

Subtask #4
26.0 / 26.0

# Verdict Execution time Memory Grader output
1 Correct 14 ms 14000 KB Output is correct
2 Correct 31 ms 19164 KB Output is correct
3 Correct 13 ms 13968 KB Output is correct
4 Correct 31 ms 18404 KB Output is correct
5 Correct 14 ms 13968 KB Output is correct
6 Correct 25 ms 18528 KB Output is correct
7 Correct 37 ms 23320 KB Output is correct
8 Correct 35 ms 17256 KB Output is correct
9 Correct 32 ms 19504 KB Output is correct
10 Correct 32 ms 20108 KB Output is correct

Subtask #5
27.0 / 27.0

# Verdict Execution time Memory Grader output
1 Correct 44 ms 40780 KB Output is correct
2 Correct 111 ms 72748 KB Output is correct
3 Correct 46 ms 41056 KB Output is correct
4 Correct 103 ms 65024 KB Output is correct
5 Correct 52 ms 41068 KB Output is correct
6 Correct 110 ms 67416 KB Output is correct
7 Correct 148 ms 73900 KB Output is correct
8 Correct 144 ms 51296 KB Output is correct
9 Correct 127 ms 51320 KB Output is correct
10 Correct 91 ms 56956 KB Output is correct
11 Correct 50 ms 41072 KB Output is correct
12 Correct 119 ms 53456 KB Output is correct