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Submission #106083

# Submission time Handle Problem Language Result Execution time Memory
106083 2019-04-16T13:34:06 Z Saboon Palindromes (APIO14_palindrome) C++14
47 / 100
 1000 ms 41828 KB 
#include <bits/stdc++.h>
 
using namespace std;
 
typedef long long ll;
 
const int maxn = 3e5 + 10;
const int base = 37;
const int mod = 1e9 + 7;

int n;
string s;
ll sa[maxn], pos[maxn], pw[maxn], hsh[maxn], rev[maxn], answer;

vector<int> seg[4 * maxn];

int get_rev(int L, int R){
	ll ret = rev[L] - rev[R + 1] * pw[R - L + 1] % mod;
	if (ret < 0)
		ret += mod;
	return ret;
}

int get_hsh(int L, int R){
	if (L == 0)
		return hsh[R];
	ll ret = hsh[R] - hsh[L - 1] * pw[R - L + 1] % mod;
	if (ret < 0)
		ret += mod;
	return ret;
}

int lcp(int fi, int se){
	int lo = 0, hi = min(n - fi + 1, n - se + 1);
	while (hi - lo > 1){
		int mid = (lo + hi) >> 1;
		if (get_hsh(fi, fi + mid - 1) == get_hsh(se, se + mid - 1))
			lo = mid;
		else
			hi = mid;
	}
	return lo;
}

bool cmp(int fi, int se){
	int lo = 0, hi = min(n - fi + 1, n - se + 1);
	while (hi - lo > 1){
		int mid = (lo + hi) >> 1;
		if (get_hsh(fi, fi + mid - 1) == get_hsh(se, se + mid - 1))
			lo = mid;
		else
			hi = mid;
	}
	if (lo == n - fi or (lo < n - se and s[fi + lo] < s[se + lo]))
		return 1;
	return 0;
}

void buildSA(){
	for (int i = 0; i < n; i++)
		sa[i] = i;
	sort(sa, sa + n, cmp);
	for (int i = 0; i < n; i++)
		pos[sa[i]] = i;
}

void check(int L, int R){
	int len = R - L + 1;
	int fi, se;
	int lo = -1, hi = pos[L];
//	cout << "checking : " << lo << " " << hi << endl;
	while (hi - lo > 1){
		int mid = (lo + hi) >> 1;
		if (lcp(L, sa[mid]) >= len)
			hi = mid;
		else
			lo = mid;
	}
	fi = hi;
	lo = pos[L], hi = n;
//	cout << "checking : " << lo << " " << hi << endl;
	while (hi - lo > 1){
		int mid = (lo + hi) >> 1;
		if (lcp(L, sa[mid]) >= len)
			lo = mid;
		else
			hi = mid;
	}
	se = lo;
//	cout << "then is : " << fi << " " << se << endl;
	answer = max(answer, 1ll * len * (se - fi + 1));
}

void get(int id, int L, int R, int idx, int len){
	for (int i = 0; i < seg[id].size() and seg[id][i] < 0; i++){
		int t = -seg[id][i];
		t --;
		t = (t - idx + 1);
		if (2 * t <= len)
			break;
//		cout << "this is palindrome : " << idx << " " << idx + 2 * t - 1 << endl;
		check(idx, idx + 2 * t - 1);
	}
	for (int i = (int)(seg[id].size()) - 1; i >= 0 and seg[id][i] > 0; i--){
		int t = seg[id][i];
		t --;
		t = (t - idx);
		if (2 * t + 1 <= len)
			break;
//		cout << "this is palindrome : " << idx << " " << idx + 2 * t << endl;
		check(idx, idx + 2 * t);
	}
	if (L + 1 == R)
		return;
	int mid = (L + R) >> 1;
	if (idx < mid)
		get(2 * id + 0, L, mid, idx, len);
	else
		get(2 * id + 1, mid, R, idx, len);
}

void add(int id, int L, int R, int l, int r, int x){
	if (L == l and R == r){
		seg[id].push_back(x);
		return;
	}
	int mid = (L + R) >> 1;
	if (l < mid)
		add(2 * id + 0, L, mid, l, min(mid, r), x);
	if (mid < r)
		add(2 * id + 1, mid, R, max(l, mid), r, x);
}

int main(){
	ios_base::sync_with_stdio(false);
	cin >> s;
	n = s.size();
	pw[0] = 1;
	for (int i = 1; i <= n; i++)
		pw[i] = pw[i - 1] * base % mod;
	for (int i = 0; i < n; i++){
		if (i == 0)
			hsh[i] = (int)(s[i] - 'a' + 1);
		else
			hsh[i] = (hsh[i - 1] * base + (int)(s[i] - 'a' + 1)) % mod;
	}
	for (int i = n - 1; i >= 0; i--)
		rev[i] = (rev[i + 1] * base + (int)(s[i] - 'a' + 1)) % mod;
	buildSA();
	for (int i = 0; i < n; i++){
		int lo = 0, hi = min(i, n - i - 1) + 1;
		while (hi - lo > 1){
			int mid = (lo + hi) >> 1;
			if (get_hsh(i - mid, i - 1) == get_rev(i + 1, i + mid))
				lo = mid;
			else
				hi = mid;
		}
		add(1, 0, n, i - lo, i + 1, i + 1);
		if (i < n - 1){
			lo = 0, hi = min(i + 2, n - i);
			while (hi - lo > 1){
				int mid = (lo + hi) >> 1;
				if (get_hsh(i - mid + 1, i) == get_rev(i + 1, i + mid))
					lo = mid;
				else
					hi = mid;
			}
			if (lo > 0)
				add(1, 0, n, i - lo + 1, i + 1, -(i+1));
		}
	}
	for (int i = 1; i < 4 * maxn; i++)
		sort(seg[i].begin(), seg[i].end());
	for (int i = 0; i < n; i++){
		int idx = sa[i];
		int len = 0;
		if (i > 0)
			len = lcp(sa[i], sa[i - 1]);
		get(1, 0, n, idx, len);
	}
	cout << answer << endl;
}

Compilation message

palindrome.cpp: In function 'void get(int, int, int, int, int)':
palindrome.cpp:95:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < seg[id].size() and seg[id][i] < 0; i++){
                  ~~^~~~~~~~~~~~~~~~

Subtask #1
8.0 / 8.0

# Verdict Execution time Memory Grader output
1 Correct 38 ms 28668 KB Output is correct
2 Correct 39 ms 28536 KB Output is correct
3 Correct 36 ms 28544 KB Output is correct
4 Correct 34 ms 28536 KB Output is correct
5 Correct 34 ms 28544 KB Output is correct
6 Correct 36 ms 28536 KB Output is correct
7 Correct 36 ms 28544 KB Output is correct
8 Correct 36 ms 28536 KB Output is correct
9 Correct 34 ms 28536 KB Output is correct
10 Correct 30 ms 28544 KB Output is correct
11 Correct 30 ms 28544 KB Output is correct
12 Correct 34 ms 28544 KB Output is correct
13 Correct 33 ms 28544 KB Output is correct
14 Correct 35 ms 28544 KB Output is correct
15 Correct 28 ms 28544 KB Output is correct
16 Correct 34 ms 28544 KB Output is correct
17 Correct 35 ms 28544 KB Output is correct
18 Correct 37 ms 28544 KB Output is correct
19 Correct 36 ms 28664 KB Output is correct
20 Correct 34 ms 28536 KB Output is correct
21 Correct 34 ms 28544 KB Output is correct
22 Correct 35 ms 28544 KB Output is correct
23 Correct 36 ms 28536 KB Output is correct
24 Correct 34 ms 28536 KB Output is correct
25 Correct 32 ms 28672 KB Output is correct
26 Correct 33 ms 28544 KB Output is correct
27 Correct 31 ms 28536 KB Output is correct
28 Correct 30 ms 28536 KB Output is correct
29 Correct 31 ms 28536 KB Output is correct
30 Correct 31 ms 28516 KB Output is correct
31 Correct 29 ms 28536 KB Output is correct
32 Correct 30 ms 28544 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 35 ms 28664 KB Output is correct
2 Correct 58 ms 28672 KB Output is correct
3 Correct 41 ms 28796 KB Output is correct
4 Correct 43 ms 28584 KB Output is correct
5 Correct 40 ms 28664 KB Output is correct
6 Correct 41 ms 28664 KB Output is correct
7 Correct 35 ms 28692 KB Output is correct
8 Correct 34 ms 28704 KB Output is correct
9 Correct 33 ms 28672 KB Output is correct
10 Correct 35 ms 28664 KB Output is correct
11 Correct 33 ms 28692 KB Output is correct
12 Correct 38 ms 28692 KB Output is correct

Subtask #3
24.0 / 24.0

# Verdict Execution time Memory Grader output
1 Correct 133 ms 29932 KB Output is correct
2 Correct 115 ms 29916 KB Output is correct
3 Correct 115 ms 30456 KB Output is correct
4 Correct 161 ms 30456 KB Output is correct
5 Correct 126 ms 29432 KB Output is correct
6 Correct 126 ms 29476 KB Output is correct
7 Correct 118 ms 29816 KB Output is correct
8 Correct 75 ms 29436 KB Output is correct
9 Correct 84 ms 29304 KB Output is correct
10 Correct 107 ms 29432 KB Output is correct

Subtask #4
0 / 26.0

# Verdict Execution time Memory Grader output
1 Execution timed out 1087 ms 41828 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #5
0 / 27.0

# Verdict Execution time Memory Grader output
1 Execution timed out 1079 ms 38272 KB Time limit exceeded
2 Halted 0 ms 0 KB -