Submission #42170

#	Time	Username	Problem	Language	Result	Execution time	Memory
42170		Aidyn_A	Palindromes (APIO14_palindrome)	C++14	73 / 100	431 ms	18688 KiB

palindrome

#include <stdio.h>
#include <bits/stdc++.h>			

#define pb push_back
#define pf push_front
#define pp pop_back
#define sz(a) (int)(a.size())
#define mp make_pair
#define F first
#define S second
#define next _next
#define prev _prev
#define left _left
#define right _right
#define y1 _y1
#define all(x) x.begin(), x.end()
#define what_is(x) #x << " is " << (x)

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int N = (int)1e5 + 123;
const ll INF = (ll)1e18 + 123;
const int inf = (int)1e9 + 123;

void megaRandom() {
	unsigned int FOR;
 	asm("rdtsc" : "=A"(FOR));
  srand(FOR);
}

int mult(int a, int b, int MOD) {
	return 1ll * a * b % MOD;
}

int add(int a, int b, int MOD) {
	a += b;
	if(a >= MOD) a -= MOD;
	return a;
}  

int subs(int a, int b, int MOD) {
	a -= b;
	if(a < 0) a += MOD;
	return a;
}

string s;
int h[3][N], P[3], pw[3][N], MOD[3];
int hr[3][N];
   
void build() {
	h[1][0] = h[2][0] = s[0];
	for(int it = 1; it <= 2; it ++)
		for(int i = 1; i < sz(s); i ++)
			h[it][i] = add(mult(h[it][i - 1], P[it], MOD[it]), s[i], MOD[it]); 
	string b = s;
	reverse(all(b));
	hr[1][0] = hr[2][0] = b[0];
	for(int it = 1; it <= 2; it ++)
		for(int i = 1; i < sz(b); i ++)
			hr[it][i] = add(mult(hr[it][i - 1], P[it], MOD[it]), b[i], MOD[it]);
}                      

pii getHash(int l, int r) {
	//assert(l >= 0 && r < sz(s) && l <= r);
	int A = subs(h[1][r], mult(h[1][l - 1], pw[1][r - l + 1], MOD[1]), MOD[1]);
	int B = subs(h[2][r], mult(h[2][l - 1], pw[2][r - l + 1], MOD[2]), MOD[2]);
	return {A, B};
}

pii getHashR(int l, int r) {
	int l1 = sz(s) - r - 1, r1 = sz(s) - l - 1;
	l = l1, r = r1;
	//assert(l >= 0 && r < sz(s) && l <= r);
	int A = subs(hr[1][r], mult(hr[1][l - 1], pw[1][r - l + 1], MOD[1]), MOD[1]);
	int B = subs(hr[2][r], mult(hr[2][l - 1], pw[2][r - l + 1], MOD[2]), MOD[2]);
	return {A, B};
}
                             
int length(int i, int j) {
	if(s[i] != s[j])
		return 0;
	int l = 0, r = min(i, sz(s) - j) + 1;
	while(r - l > 1) {
		int mid = (l + r) >> 1;
		if(i - mid >= 0 && j + mid < sz(s) && getHash(i - mid, i) == getHashR(j, j + mid))
			l = mid;
		else 	
			r = mid;
	}
	return l;              	
}

map<pii, int> newId;
int vtr;
vector<int> g[N];
int chest[N], dlina[N];
int pr[N];

void calcOdd() {
	for(int i = 0; i < sz(s); i ++) {
		int tmp = length(i, i), bmp = tmp;
		int prev = -1;
		while(tmp >= 0) {
		  int kepka = newId[getHash(i - tmp, i + tmp)];
		  if(!kepka) {
		  	newId[getHash(i - tmp, i + tmp)] = ++ vtr;
		  	dlina[vtr] = tmp * 2 + 1;
		  	if(prev != -1) {
		  		g[vtr].pb(prev);
        	pr[prev] = vtr;
        }
		  	prev = vtr;
		  } else {
		  	if(prev != -1) {
		  		g[kepka].pb(prev);
		  		pr[prev] = kepka;
		  	}
		  	break;
		  }
			tmp --;			
		}
		chest[newId[getHash(i - bmp, i + bmp)]] ++;
	}
}

int sub[N];
ll res;

void dfs(int x) {
	sub[x] += chest[x];
	for(auto to : g[x]) {
		dfs(to);
		sub[x] += sub[to];
	}
	res = max(res, 1ll * sub[x] * dlina[x]);	
}

void clear() {
	memset(sub, 0, sizeof sub);
	for(int i = 1; i <= vtr; i ++) 
		g[i].clear();
	vtr = 0;
	memset(chest, 0, sizeof chest);
	memset(dlina, 0, sizeof dlina);
	memset(pr, 0, sizeof pr);
	newId.clear();
}

void calcEven() {
	for(int i = 1; i < sz(s); i ++) {
		if(s[i - 1] != s[i])
			continue;
		int tmp = length(i - 1, i), bmp = tmp;
		int prev = -1;
		while(tmp >= 0) {
			int kepka = newId[getHash(i - tmp - 1, i + tmp)];
		  if(!kepka) {
		  	newId[getHash(i - tmp - 1, i + tmp)] = ++ vtr;
		  	dlina[vtr] = (tmp + 1) * 2;
		  	if(prev != -1) {
		  		g[vtr].pb(prev);
		  		pr[prev] = vtr;
		  	}
		  	prev = vtr;
		  } else { 
		  	if(prev != -1) {
		  		g[kepka].pb(prev);
		  		pr[prev] = kepka;
				}
		  	break;
      }
			tmp --;			
		}
		chest[newId[getHash(i - bmp - 1, i + bmp)]] ++;
	}
}

int main() {
	megaRandom();
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	P[1] = 31, P[2] = 39;
	MOD[1] = (int)1e9 + 7, MOD[2] = (int)1e9 + 9;
	for(int it = 1; it <= 2; it ++) {
		pw[it][0] = 1;
		for(int i = 1; i <= N - 123; i ++)
			pw[it][i] = mult(pw[it][i - 1], P[it], MOD[it]); 
	}
	cin >> s;
	build();
	calcOdd();
	for(int i = 1; i <= vtr; i ++) { 
 	  if(pr[i]) continue;
		dfs(i);
	}
	clear();	
	calcEven();		
	for(int i = 1; i <= vtr; i ++)  {
		if(pr[i]) continue;
		dfs(i);
	}
	cout << res;
	return 0;  
}

• Subtask 1: 8 / 8
• Subtask 2: 15 / 15
• Subtask 3: 24 / 24
• Subtask 4: 26 / 26
• Subtask 5: 0 / 27