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Submission #106093

# Submission time Handle Problem Language Result Execution time Memory
106093 2019-04-16T13:50:16 Z Saboon Palindromes (APIO14_palindrome) C++14
47 / 100
 1000 ms 39936 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;
int sa[maxn], pos[maxn], pw[maxn], hsh[maxn], rev[maxn], lmq[19][maxn], rmq[19][maxn];
ll answer;

vector<int> seg[4 * maxn];

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

/*
int lcp(int fi, int se){
	if (fi == se)
		return n - fi;
	fi = pos[fi], se = pos[se];
	if (fi > se)
		swap(fi, se);
	int len = se - fi;
	len = log2(len);
	return min(rmq[len][fi], lmq[len][se]);
}*/

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;
/*	memset(rmq, 63, sizeof rmq);
	memset(lmq, 63, sizeof lmq);
	for (int i = 0; i < n - 1; i++){
		int tmp = lcp(sa[i], sa[i + 1]);
		rmq[0][i] = tmp;
		lmq[0][i + 1] = tmp;
	}
	for (int i = 0; i < 18; i++)
		for (int j = 0; j + (1 << i) < n; j++)
			rmq[i + 1][j] = min(rmq[i][j], rmq[i][j + (1 << i)]);
	for (int i = 0; i < 18; i++)
		for (int j = n - 1; j - (1 << i) >= 0; j--)
			lmq[i + 1][j] = min(lmq[i][j], lmq[i][j - (1 << i)]);
*/
}

void check(int L, int R){
	int len = R - L + 1;
	int fi, se;
	int lo = -1, hi = pos[L];
	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;
	while (hi - lo > 1){
		int mid = (lo + hi) >> 1;
		if (lcp(L, sa[mid]) >= len)
			lo = mid;
		else
			hi = mid;
	}
	se = lo;
	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;
		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;
		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] = 1ll * 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] = (1ll * hsh[i - 1] * base + (int)(s[i] - 'a' + 1)) % mod;
	}
	for (int i = n - 1; i >= 0; i--)
		rev[i] = (1ll * 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:119:20: 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 30 ms 28544 KB Output is correct
2 Correct 32 ms 28544 KB Output is correct
3 Correct 31 ms 28544 KB Output is correct
4 Correct 35 ms 28536 KB Output is correct
5 Correct 35 ms 28544 KB Output is correct
6 Correct 33 ms 28536 KB Output is correct
7 Correct 29 ms 28544 KB Output is correct
8 Correct 35 ms 28544 KB Output is correct
9 Correct 35 ms 28536 KB Output is correct
10 Correct 36 ms 28536 KB Output is correct
11 Correct 35 ms 28536 KB Output is correct
12 Correct 34 ms 28544 KB Output is correct
13 Correct 33 ms 28544 KB Output is correct
14 Correct 38 ms 28544 KB Output is correct
15 Correct 32 ms 28544 KB Output is correct
16 Correct 31 ms 28544 KB Output is correct
17 Correct 37 ms 28544 KB Output is correct
18 Correct 34 ms 28536 KB Output is correct
19 Correct 36 ms 28544 KB Output is correct
20 Correct 36 ms 28544 KB Output is correct
21 Correct 40 ms 28536 KB Output is correct
22 Correct 36 ms 28580 KB Output is correct
23 Correct 36 ms 28536 KB Output is correct
24 Correct 34 ms 28544 KB Output is correct
25 Correct 29 ms 28576 KB Output is correct
26 Correct 30 ms 28544 KB Output is correct
27 Correct 34 ms 28544 KB Output is correct
28 Correct 34 ms 28540 KB Output is correct
29 Correct 31 ms 28516 KB Output is correct
30 Correct 38 ms 28544 KB Output is correct
31 Correct 38 ms 28544 KB Output is correct
32 Correct 36 ms 28516 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 37 ms 28768 KB Output is correct
2 Correct 34 ms 28672 KB Output is correct
3 Correct 43 ms 28664 KB Output is correct
4 Correct 40 ms 28700 KB Output is correct
5 Correct 39 ms 28664 KB Output is correct
6 Correct 39 ms 28696 KB Output is correct
7 Correct 42 ms 28616 KB Output is correct
8 Correct 40 ms 28660 KB Output is correct
9 Correct 36 ms 28660 KB Output is correct
10 Correct 35 ms 28544 KB Output is correct
11 Correct 37 ms 28672 KB Output is correct
12 Correct 36 ms 28664 KB Output is correct

Subtask #3
24.0 / 24.0

# Verdict Execution time Memory Grader output
1 Correct 105 ms 29752 KB Output is correct
2 Correct 124 ms 29816 KB Output is correct
3 Correct 118 ms 30280 KB Output is correct
4 Correct 154 ms 30340 KB Output is correct
5 Correct 112 ms 29176 KB Output is correct
6 Correct 117 ms 29368 KB Output is correct
7 Correct 113 ms 29688 KB Output is correct
8 Correct 78 ms 29236 KB Output is correct
9 Correct 71 ms 29068 KB Output is correct
10 Correct 111 ms 29296 KB Output is correct

Subtask #4
0 / 26.0

# Verdict Execution time Memory Grader output
1 Execution timed out 1065 ms 39936 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 1074 ms 33672 KB Time limit exceeded
2 Halted 0 ms 0 KB -