oj.uz

Submission #162348

# Submission time Handle Problem Language Result Execution time Memory
162348 2019-11-07T16:00:44 Z amoo_safar Palindromes (APIO14_palindrome) C++14
47 / 100
 1000 ms 66760 KB 
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>

#define pb push_back
#define F first
#define S second
#define all(x) x.begin(), x.end()
#define debug(x) cerr << #x << " : " << x << '\n'
#define int ll

using namespace std;
using namespace __gnu_pbds;

typedef long long ll;
typedef long double ld;
typedef string str;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
typedef pair<pll, pll> node;
typedef tree<ll, null_type, less<ll>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;

const ll Mod = 1000000009LL;
const int Maxn = 3e5 + 10;
const int Maxk = 60;
const ll Inf = 2242545357980376863LL;
const ll Log = 20;
const ll Base = 998244353;

int Rank[Log][Maxn], n;
int idx[Maxn];
ll ph[Maxn], phr[Maxn], pw[Maxn];
pii a[Maxn];
str s;

ll get(int l, int r){
	return (ph[r] - (ph[l]*pw[r - l] % Mod) + Mod) % Mod;
}
ll get_rev(int l, int r){
	return (phr[l] - (phr[r]*pw[r - l] % Mod) + Mod) % Mod;
}

int pal_range(int l, int r){
	int L = 0, R = min(n - r, l) + 1, mid;
	
	//int res = 0;
	//for(int i = 0; i < R - 1; i ++) if(s[l - 1 - i] != s[r + i]) return i;
	//return R - 1;
	
	while(L + 1 < R){
		mid = (L + R) >> 1;
		if(get(l - mid, l) == get_rev(r, r + mid)) L = mid;
		else R = mid;
	}
	return L;
}

int pal[Maxn];


int eq_range(int l1, int l2){
	int L = 0, R = min(n - l1, n - l2) + 1, mid;
	//for(int i = 0; i + 1 < R; i++) if(s[i + l1] != s[i + l2]) return i;
	//return R - 1;
	while(L + 1 < R){
		mid = (L + R) >> 1;
		if(get(l1, l1 + mid) == get(l2, l2 + mid)) L = mid;
		else R = mid;
	}
	return L;
}
int eq[Maxn];

int f[Maxn], f2[Maxn];

vector<int> V;
stack<int> sta;

ll solve(){
	while(!sta.empty()) sta.pop();
	ll N = V.size();
	//cerr << "N : " << N << '\n';
	sta.push(0);
	for(int i = 1; i < N-1; i++){
		//cerr << i << " " << V[i] << '\n';
		while(V[sta.top()] > V[i]) sta.pop();
		f[i] = sta.top();
		sta.push(i);
	}
	//cerr << "S" << '\n';
	while(!sta.empty()) sta.pop();
	sta.push(N-1);
	for(int i = N-2; i > 0; i--){
		while(V[sta.top()] >= V[i]) sta.pop();
		f2[i] = sta.top();
		sta.push(i);
	}
	ll res = 0;
	
	for(int i = 1; i < N - 1; i++)
		res = max(res, 1LL * (f2[i] - f[i]) * V[i]);
	return res;
}

int32_t main(){
	ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
	pw[0] = 1;
	for(int i = 1; i < Maxn; i++) pw[i] = (pw[i - 1] * Base) % Mod;
	
	cin >> s;
	n = s.size();
	
	ph[0] = 0;
	for(int i = 1; i <= n; i++) ph[i] = (ph[i - 1] * Base + s[i - 1]) % Mod;
	phr[n] = 0;
	for(int i = n - 1; i >= 0; i--) phr[i] = (phr[i + 1] * Base + s[i]) % Mod;
	//cerr << get(0, 2) << " " << get(n-2, n) << '\n';
	
	for(int i = 0; i < n; i++) Rank[0][i] = s[i];
	int st;
	for(int l = 1; l < Log; l++){
		st = (1 << (l - 1));
		for(int i = 0; i < n; i++){
			a[i].F = Rank[l - 1][i];
			a[i].S = (i + st < n ? Rank[l - 1][i + st] : -1); 
		}
		sort(a, a + n);
		for(int i = 0; i < n; i++)
			Rank[l][i] = lower_bound(a, a + n, pii(Rank[l - 1][i], (i + st < n ? Rank[l - 1][i + st] : -1) )) - a;
	}
	for(int i = 0; i < n; i++) idx[Rank[Log - 1][i]] = i;
	//cerr << '\n';
	//for(int i = 0; i < n; i++) cerr << s.substr(idx[i], n) << '\n';
	
	for(int i = 0; i < n - 1; i++) eq[i] = eq_range(idx[i], idx[i + 1]);
	//for(int i = 0; i < n - 1; i++) cerr << eq[i] << ' ';
	//cerr << '\n';
	
	
	ll ans = 0;
	
	for(int i = 0; i < n; i++) pal[i] = pal_range(i + 1, i);
	//for(int i = 0; i < n; i++) cerr << pal[i] << ' ';
	//cerr << '\n';
	
	for(int x = 1; x <= n; x++){
		ll cnt = (pal[idx[0]] >= x);
		ans = max(ans, cnt * (x + x - 1));
		for(int i = 1; i < n; i++){
			if(eq[i - 1] < x) cnt = 0;
			cnt += (pal[idx[i]] >= x);
			//cerr << cnt << '\n';
			ans = max(ans, cnt * (x + x - 1));
		}
	}
	/*
	V.pb(-2);
	for(int i = 0; i < n - 1; i++) V.pb( 2 * min(eq[i], min(pal[idx[i]], pal[idx[i + 1]])) - 1 );
	V.pb(-2);
	//for(auto x : V) cerr << x << ' '; cerr << '\n';
	ans = max(ans, 2LL * (*max_element(pal, pal + n)) - 1);
	
	ans = max(ans, solve());
	*/
	
	for(int i = 0; i < n; i++) pal[i] = pal_range(i, i);
	//for(int i = 0; i < n; i++) cerr << pal[i] << ' ';
	//cerr << '\n';
	/*
	V.clear();
	V.pb(-2);
	for(int i = 0; i < n - 1; i++) V.pb( 2 * min(eq[i], min(pal[idx[i]], pal[idx[i + 1]])) );
	V.pb(-2);
	//for(auto x : V) cerr << x << ' '; cerr << '\n';
	ans = max(ans, 2LL * (*max_element(pal, pal + n)));
	
	ans = max(ans, solve());
	*/
	
	for(int x = 1; x <= n; x++){
		ll cnt = (pal[idx[0]] >= x);
		ans = max(ans, cnt * (x + x - 1));
		for(int i = 1; i < n; i++){
			if(eq[i - 1] < x) cnt = 0;
			cnt += (pal[idx[i]] >= x);
			ans = max(ans, cnt * (x + x));
		}
	}
	
	cout << ans;
	return 0;
}

/*
abacaba

*/

Subtask #1
8.0 / 8.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 2936 KB Output is correct
2 Correct 6 ms 2936 KB Output is correct
3 Correct 6 ms 2936 KB Output is correct
4 Correct 6 ms 2808 KB Output is correct
5 Correct 6 ms 2936 KB Output is correct
6 Correct 6 ms 2936 KB Output is correct
7 Correct 6 ms 2936 KB Output is correct
8 Correct 6 ms 2936 KB Output is correct
9 Correct 6 ms 2936 KB Output is correct
10 Correct 6 ms 2936 KB Output is correct
11 Correct 6 ms 3064 KB Output is correct
12 Correct 6 ms 2936 KB Output is correct
13 Correct 6 ms 2936 KB Output is correct
14 Correct 6 ms 2936 KB Output is correct
15 Correct 6 ms 2936 KB Output is correct
16 Correct 6 ms 2936 KB Output is correct
17 Correct 6 ms 2936 KB Output is correct
18 Correct 6 ms 2936 KB Output is correct
19 Correct 6 ms 2936 KB Output is correct
20 Correct 6 ms 2956 KB Output is correct
21 Correct 6 ms 2908 KB Output is correct
22 Correct 6 ms 2936 KB Output is correct
23 Correct 6 ms 2936 KB Output is correct
24 Correct 6 ms 2936 KB Output is correct
25 Correct 6 ms 2936 KB Output is correct
26 Correct 6 ms 2936 KB Output is correct
27 Correct 6 ms 2936 KB Output is correct
28 Correct 7 ms 2936 KB Output is correct
29 Correct 6 ms 2936 KB Output is correct
30 Correct 6 ms 2936 KB Output is correct
31 Correct 6 ms 2936 KB Output is correct
32 Correct 6 ms 2936 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 12 ms 3064 KB Output is correct
2 Correct 12 ms 3064 KB Output is correct
3 Correct 12 ms 3064 KB Output is correct
4 Correct 12 ms 3064 KB Output is correct
5 Correct 11 ms 3064 KB Output is correct
6 Correct 11 ms 3064 KB Output is correct
7 Correct 13 ms 3192 KB Output is correct
8 Correct 12 ms 3064 KB Output is correct
9 Correct 13 ms 3064 KB Output is correct
10 Correct 13 ms 3064 KB Output is correct
11 Correct 13 ms 3064 KB Output is correct
12 Correct 12 ms 3064 KB Output is correct

Subtask #3
24.0 / 24.0

# Verdict Execution time Memory Grader output
1 Correct 415 ms 5084 KB Output is correct
2 Correct 449 ms 5112 KB Output is correct
3 Correct 407 ms 4984 KB Output is correct
4 Correct 421 ms 5112 KB Output is correct
5 Correct 524 ms 5112 KB Output is correct
6 Correct 542 ms 5076 KB Output is correct
7 Correct 425 ms 5112 KB Output is correct
8 Correct 509 ms 5112 KB Output is correct
9 Correct 514 ms 5080 KB Output is correct
10 Correct 533 ms 4988 KB Output is correct

Subtask #4
0 / 26.0

# Verdict Execution time Memory Grader output
1 Execution timed out 1070 ms 24356 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 1068 ms 66760 KB Time limit exceeded
2 Halted 0 ms 0 KB -