oj.uz

Submission #670225

# Submission time Handle Problem Language Result Execution time Memory
670225 2022-12-08T10:23:46 Z NothingXD Palindromes (APIO14_palindrome) C++17
100 / 100
 865 ms 26900 KB 
#include<bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
/*typedef __uint128_t L;
struct FastMod {
  ull b, m;
  FastMod(ull b) : b(b), m(ull((L(1) << 64) / b)) {}
  ull reduce(ull a) {
    ull q = (ull)((L(m) * a) >> 64);
    ull r = a - q * b; // can be proven that 0 <= r < 2*b
    return r >= b ? r - b : r;
  }
};
FastMod FM(2);*/
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

void debug_out() { cerr << endl; }

template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
	cerr << " " << H;
	debug_out(T...);
}

#define debug(...) cerr << "(" << #__VA_ARGS__ << "):", debug_out(__VA_ARGS__)
#define all(x) x.begin(), x.end()
#define MP(x, y) make_pair(x, y)
#define F first
#define S second

//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const int maxn = 3e5 + 10;


int base[2] = {313, 369}, mod[2] = {(int)1e9 + 7, (int)1e9 + 9};
int pw[maxn][2];
struct HSH{
	int hsh[maxn][2];
	HSH(){};
	HSH(string s){
		memset(hsh, 0, sizeof hsh);
		int n = s.size();
		for (int i = 1; i <= n; i++){
			for (int j = 0; j < 2; j++){
				hsh[i][j] = (1ll * hsh[i-1][j] * base[j] + s[i-1] - 'a' + 1) % mod[j];
			}
		}
	}
	pii gethsh(int l, int r){
		l--;
		int res[2];
		for (int i = 0; i < 2; i++){
			res[i] = (1ll * hsh[r][i] - 1ll * hsh[l][i] * pw[r-l][i] % mod[i] + 1ll * mod[i]) % mod[i];
		}
		return {res[0], res[1]};
	}
};

int n, suf[maxn], rnk[maxn << 1], tmp[maxn], lcp[maxn], dsu[maxn], a[maxn], cnt[maxn];
int W = 1;
string s;

int getdsu(int v){
	return (dsu[v] == -1? v: dsu[v] = getdsu(dsu[v]));
}

void merge(int u, int v){
	u = getdsu(u);
	v = getdsu(v);
	dsu[v] = u;
	cnt[u] += cnt[v];
}

bool scmp(int x, int y){
	return (rnk[x] == rnk[y]? rnk[x+W] < rnk[y+W]: rnk[x] < rnk[y]);
}

void suffarr(string &s){
	int n = s.size();
	for (int i = 0; i < n; i++){
		rnk[i] = s[i] - 'a' + 1;
		suf[i] = i;
	}
	for (;; W <<= 1){
		sort(suf, suf + n, scmp);
		tmp[suf[0]] = 1;
		for (int i = 1; i < n; i++){
			tmp[suf[i]] = tmp[suf[i-1]] + scmp(suf[i-1], suf[i]);
		}
		for (int i = 0; i < n; i++) rnk[i] = tmp[i];
		if (rnk[suf[n-1]] == n) return;
	}
}

void buildlcp(string &s){
	int n = s.size();
	int k = 0;
	for (int i = 0; i < n; i++){
		if (rnk[i] == n) continue;
		while (i + k < n && suf[rnk[i]] + k < n && s[i+k] == s[suf[rnk[i]]+k]) k++;
		lcp[rnk[i]] = k;
		if (k) k--;
	}
}

int main(){
	ios_base::sync_with_stdio(false); cin.tie(0);

	pw[0][0] = pw[0][1] = 1;
	for (int i = 1; i < maxn; i++){
		for (int j = 0; j < 2; j++){
			pw[i][j] = 1ll * pw[i-1][j] * base[j] % mod[j];
		}
	}
	cin >> s;
	string t = s;
	reverse(all(t));
	HSH S(s);
	HSH T(t);
	n = s.size();
	suffarr(s);
	buildlcp(s);

	for (int i = 1; i <= n; i++){
		int l = 0, r = min(i, n-i+2);
		while(l + 1 < r){
			int mid = (l + r) >> 1;
			int tmp = n + 2 - i;
			if (S.gethsh(i-mid, i+mid-1) == T.gethsh(tmp-mid, tmp+mid-1)) l = mid;
			else r = mid;
		}
		a[i] = l;
	}

	vector<pair<pii,int>> Q;

	for (int i = 1; i <= n; i++){
		if (i != n) Q.push_back({{lcp[i], i}, 1});
		Q.push_back({{a[i], rnk[i-1]}, 2});
	}

	memset(dsu, -1, sizeof dsu);
	memset(cnt, 0, sizeof cnt);

	sort(all(Q), greater<pair<pii,int>>());

	ll ans = 0;

	for (auto [x, y]: Q){
		if (y == 1){
			merge(x.S, x.S + 1);
			int v = getdsu(x.S);
			ans = max(ans, 2ll * cnt[v] * x.F);
		}
		else{
			int v = getdsu(x.S);
			cnt[v]++;
			ans = max(ans, 2ll * cnt[v] * x.F);
		}
	}

	for (int i = 1; i <= n; i++){
		int l = 0, r = min(i, n-i+1);
		while(l + 1 < r){
			int mid = (l + r) >> 1;
			int tmp = n + 1 - i;
			if (S.gethsh(i-mid, i+mid) == T.gethsh(tmp-mid, tmp+mid)) l = mid;
			else r = mid;
		}
		a[i] = l+1;
	}

	Q.clear();

	for (int i = 1; i <= n; i++){
		if (i != n) Q.push_back({{lcp[i], i}, 1});
		Q.push_back({{a[i], rnk[i-1]}, 2});
	}

	memset(dsu, -1, sizeof dsu);
	memset(cnt, 0, sizeof cnt);

	sort(all(Q), greater<pair<pii,int>>());

	for (auto [x, y]: Q){
		if (y == 1){
			merge(x.S, x.S + 1);
			int v = getdsu(x.S);
			ans = max(ans, 1ll * (2 * x.F - 1) * cnt[v]);
		}
		else{
			int v = getdsu(x.S);
			cnt[v]++;
			ans = max(ans, 1ll * (2 * x.F - 1) * cnt[v]);
		}
	}

	cout << ans << '\n';

	return 0;
}

Subtask #1
8.0 / 8.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 9684 KB Output is correct
2 Correct 8 ms 9684 KB Output is correct
3 Correct 8 ms 9684 KB Output is correct
4 Correct 8 ms 9684 KB Output is correct
5 Correct 9 ms 9684 KB Output is correct
6 Correct 8 ms 9732 KB Output is correct
7 Correct 9 ms 9684 KB Output is correct
8 Correct 8 ms 9668 KB Output is correct
9 Correct 8 ms 9676 KB Output is correct
10 Correct 8 ms 9676 KB Output is correct
11 Correct 8 ms 9684 KB Output is correct
12 Correct 8 ms 9672 KB Output is correct
13 Correct 8 ms 9684 KB Output is correct
14 Correct 8 ms 9684 KB Output is correct
15 Correct 8 ms 9620 KB Output is correct
16 Correct 8 ms 9684 KB Output is correct
17 Correct 8 ms 9680 KB Output is correct
18 Correct 8 ms 9680 KB Output is correct
19 Correct 8 ms 9668 KB Output is correct
20 Correct 9 ms 9668 KB Output is correct
21 Correct 8 ms 9684 KB Output is correct
22 Correct 9 ms 9684 KB Output is correct
23 Correct 9 ms 9672 KB Output is correct
24 Correct 8 ms 9684 KB Output is correct
25 Correct 8 ms 9684 KB Output is correct
26 Correct 8 ms 9684 KB Output is correct
27 Correct 8 ms 9672 KB Output is correct
28 Correct 8 ms 9672 KB Output is correct
29 Correct 8 ms 9660 KB Output is correct
30 Correct 8 ms 9684 KB Output is correct
31 Correct 8 ms 9684 KB Output is correct
32 Correct 8 ms 9672 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 9796 KB Output is correct
2 Correct 9 ms 9812 KB Output is correct
3 Correct 9 ms 9812 KB Output is correct
4 Correct 9 ms 9796 KB Output is correct
5 Correct 10 ms 9812 KB Output is correct
6 Correct 10 ms 9804 KB Output is correct
7 Correct 10 ms 9812 KB Output is correct
8 Correct 10 ms 9812 KB Output is correct
9 Correct 10 ms 9812 KB Output is correct
10 Correct 9 ms 9800 KB Output is correct
11 Correct 9 ms 9812 KB Output is correct
12 Correct 9 ms 9812 KB Output is correct

Subtask #3
24.0 / 24.0

# Verdict Execution time Memory Grader output
1 Correct 28 ms 10420 KB Output is correct
2 Correct 23 ms 10344 KB Output is correct
3 Correct 30 ms 10252 KB Output is correct
4 Correct 27 ms 10324 KB Output is correct
5 Correct 23 ms 10248 KB Output is correct
6 Correct 25 ms 10248 KB Output is correct
7 Correct 24 ms 10304 KB Output is correct
8 Correct 20 ms 10324 KB Output is correct
9 Correct 20 ms 10332 KB Output is correct
10 Correct 25 ms 10316 KB Output is correct

Subtask #4
26.0 / 26.0

# Verdict Execution time Memory Grader output
1 Correct 239 ms 15124 KB Output is correct
2 Correct 215 ms 14792 KB Output is correct
3 Correct 257 ms 14408 KB Output is correct
4 Correct 252 ms 14448 KB Output is correct
5 Correct 220 ms 14452 KB Output is correct
6 Correct 211 ms 14408 KB Output is correct
7 Correct 223 ms 14460 KB Output is correct
8 Correct 151 ms 14408 KB Output is correct
9 Correct 227 ms 14452 KB Output is correct
10 Correct 237 ms 14572 KB Output is correct

Subtask #5
27.0 / 27.0

# Verdict Execution time Memory Grader output
1 Correct 774 ms 26676 KB Output is correct
2 Correct 680 ms 26844 KB Output is correct
3 Correct 865 ms 26772 KB Output is correct
4 Correct 789 ms 26772 KB Output is correct
5 Correct 796 ms 26780 KB Output is correct
6 Correct 741 ms 26864 KB Output is correct
7 Correct 729 ms 26852 KB Output is correct
8 Correct 492 ms 26768 KB Output is correct
9 Correct 488 ms 26780 KB Output is correct
10 Correct 835 ms 26780 KB Output is correct
11 Correct 699 ms 26780 KB Output is correct
12 Correct 758 ms 26900 KB Output is correct