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Submission #259060

# Submission time Handle Problem Language Result Execution time Memory
259060 2020-08-07T06:14:44 Z pure_mem Palindromes (APIO14_palindrome) C++14
73 / 100
 1000 ms 60952 KB 
#include <bits/stdc++.h>
 
#define ll long long
#define X first
#define Y second
#define MP make_pair
 
using namespace std;
 
const int N = 3e5 + 3;
 
struct sarr{
	ll mod1 = 1e9 + 7, mod2 = 1e9 + 9, mod3 = 1e9 + 21;
	ll pr1[N], pr2[N], pr3[N];
	ll hs1[N], hs2[N], hs3[N], rhs1[N], rhs2[N], rhs3[N];
	int sf[N], poses[N], lcm[N], sp[19][N], lg[N];
	string s;
 
	set< pair< int, int > > were;
 
	void init(string temp){
		s = temp;
		pr1[0] = pr2[0] = pr3[0] = 1;
		lg[1] = 0;
		for(int i = 1;i < N;i++){
			pr1[i] = pr1[i - 1] * 29 % mod1;
			pr2[i] = pr2[i - 1] * 31 % mod2;
			pr3[i] = pr3[i - 1] * 37 % mod3;
			if(i > 1)
				lg[i] = lg[i / 2] + 1;
		}
		for(int i = 0;i < (int)temp.size();i++){
			sf[i + 1] = i + 1;
			hs1[i + 1] = (hs1[i] + (temp[i] - 'a' + 1) * pr1[i]) % mod1;
			hs2[i + 1] = (hs2[i] + (temp[i] - 'a' + 1) * pr2[i]) % mod2;
			hs3[i + 1] = (hs3[i] + (temp[i] - 'a' + 1) * pr3[i]) % mod3;	
		}
		for(int i = 0;i < (int)temp.size();i++){
			int j = (int)temp.size() - i - 1;
			rhs1[j + 1] = (rhs1[j + 2] + (temp[j] - 'a' + 1) * pr1[i]) % mod1;
			rhs2[j + 1] = (rhs2[j + 2] + (temp[j] - 'a' + 1) * pr2[i]) % mod2;
			rhs3[j + 1] = (rhs3[j + 2] + (temp[j] - 'a' + 1) * pr3[i]) % mod3;	
		}
		this->build_sf();
		for(int i = 1;i < (int)temp.size();i++){
			lcm[i] = this->get_lcm(sf[i], sf[i + 1]);
		//	cerr << lcm[i] << " ";
		}
		//cerr << endl;
		for(int i = 1;i <= (int)temp.size();i++){
			sp[0][i] = lcm[i];
		//	cerr << sf[i] << " ";
			poses[sf[i]] = i;
		}
		for(int i = 1;i < 19;i++){
			for(int j = 1;j + (1 << i) - 1 <= (int)temp.size();j++){
				sp[i][j] = min(sp[i - 1][j], sp[i - 1][j + (1 << (i - 1))]);
			}
		}
	}

	void build_sf(){
		string temp = s;
		temp += "#"; 
		int n = temp.size();
		vector<int> cl(n, 0), pn(n, 0), cn(n, 0), p(n, 0), cnt(n, 0);
		for(int i = 0;i < n;i++)
			p[i] = i;
		sort(p.begin(), p.end(), [this](int x, int y){
			if(s[x] < s[y])
				return 1;
			return 0;
		});
		int classes = 0;
		for(int i = 1;i < n;i++){
			if(s[p[i]] != s[p[i - 1]])
				classes++;
			cl[p[i]] = classes;
		}
		for(int it = 0;(1 << it) < n;it++){
			for(int i = 0;i < n;i++){
				pn[i] = p[i] - (1 << it);
				if(pn[i] < 0)
					pn[i] += n;
			}
			cnt.assign(cnt.size(), 0);
			for(int i = 0;i < n;i++){
				++cnt[cl[pn[i]]];
			}
			for(int i = 1;i <= classes;i++){
				cnt[i] += cnt[i - 1];	
			}
			for(int i = n - 1;i >= 0;i--){
				p[--cnt[cl[pn[i]]]] = pn[i];
			}
			cn[p[0]] = 0;
			classes = 0;
			for(int i = 1;i < n;i++){
				int m1 = (p[i] + (1 << it)) % n, m2 = (p[i - 1] + (1 << it)) % n;
				if(cl[p[i]] != cl[p[i - 1]] || cl[m1] != cl[m2])
					classes++;
				cn[p[i]] = classes;
			}
			for(int i = 0;i < n;i++)
				cl[i] = cn[i];
		}
		for(int i = 2;i <= n;i++){
			sf[i - 1] = p[i - 1] + 1;	
		}
	}
 
	bool check(int l, int r){
		bool can = 1;
	//	return can;
		ll add1 = 0, add2 = 0;
		if(l > (int)s.size() - r + 1)
			add2 = l - ((int)s.size() - r + 1);
		else
			add1 = (int)s.size() - r + 1 - l;
		if((hs1[r] - hs1[l - 1] + mod1) % mod1 * pr1[add1] % mod1 != (rhs1[l] - rhs1[r + 1] + mod1) % mod1 * pr1[add2] % mod1)
			can = 0;
		if((hs2[r] - hs2[l - 1] + mod2) % mod2 * pr2[add1] % mod2 != (rhs2[l] - rhs2[r + 1] + mod2) % mod2 * pr2[add2] % mod2)
			can = 0;
		//if((hs3[r] - hs3[l - 1] + mod3) % mod3 * pr3[add1] % mod3 != (rhs3[l] - rhs3[r + 1] + mod3) % mod3 * pr3[add2] % mod3)
		//	can = 0;
		return can;
	}
 
	bool check_eq(int l1, int r1, int l2, int r2){
		bool can = 1;
		if(l1 > l2)
			swap(l1, l2), swap(r1, r2);
		if(((hs1[r1] - hs1[l1 - 1] + mod1) % mod1) * pr1[l2 - l1] % mod1 != (hs1[r2] - hs1[l2 - 1] + mod1) % mod1)
			can = 0;
		if(((hs2[r1] - hs2[l1 - 1] + mod2) % mod2) * pr2[l2 - l1] % mod2 != (hs2[r2] - hs2[l2 - 1] + mod2) % mod2)
			can = 0;
		if(((hs3[r1] - hs3[l1 - 1] + mod3) % mod3) * pr3[l2 - l1] % mod3 != (hs3[r2] - hs3[l2 - 1] + mod3) % mod3)
			can = 0;
		return can;
	}
 
	int get_lcm(int l, int r){
		if(l > r)
			swap(l, r);
		int tl = 1, tr = (int)s.size() - r + 1, tp = 0;
		while(tl <= tr){
			int tm = (tl + tr) / 2;
			if(this->check_eq(l, l + tm - 1, r, r + tm - 1))
				tl = tm + 1, tp = tm;
			else
				tr = tm - 1;
		}
		return tp;
	}
 
	bool is_less(int l, int r){
		int lc = this->get_lcm(l, r);
		if(l + lc - 1 == (int)s.size())
			return 1;
		else if(r + lc - 1 == (int)s.size())
			return 0;
		return s[l + lc - 1] < s[r + lc - 1];
	}
 
	bool is_were(int l, int r){
		ll hash1 = ((hs1[r] - hs1[l - 1] + mod1) % mod1) * pr1[(int)s.size() - l] % mod1;
		ll hash2 = ((hs2[r] - hs2[l - 1] + mod2) % mod2) * pr2[(int)s.size() - l] % mod2;
		//ll hash3 = ((hs3[r] - hs3[l - 1] + mod3) % mod3) * pr3[(int)s.size() - l] % mod3;
		if(were.count(MP(hash1, hash2)))
			return 0;
		were.insert(MP(hash1, hash2));
		return 1;
	}
 
	int lcm_min(int l, int r){
		if(l == r)
			return (int)s.size() - l + 1;
		r -= 1;
		int lens = (r - l + 1);
		//cerr << lg[lens] << " " << lens << " " << sp[lg[lens]][l] << "s\n";
		return min(sp[lg[lens]][l], sp[lg[lens]][r - (1 << lg[lens]) + 1]);	
	}
 
	int get_cnt(int l, int r){
		int idx = poses[l];
		int tl = 1, tr = idx - 1, res = 1;
		while(tl <= tr){
			int tm = (tl + tr) / 2;
			if(this->lcm_min(tm, idx) >= r - l + 1){
				tr = tm - 1, res = idx - tm + 1;
			}
			else{
				tl = tm + 1;
			}
		}
		int tp = 1;
		tl = idx + 1, tr = (int)s.size();
		while(tl <= tr){
			int tm = (tl + tr) / 2;
			if(this->lcm_min(idx, tm) >= r - l + 1){
				tl = tm + 1, tp = tm - idx + 1;
			}
			else{
				tr = tm - 1;
			}
		}
	//	cerr << res << " " << tp << "\n";
		return res + tp - 1;
	}
}g;
 
int main () {
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
 
    double start_f = clock();

    cin >> g.s;
    //cerr << g.s << "\n";
    ll res = 0;
    g.init(g.s);
    int n = g.s.size();
   // cerr << g.check(26, 27) << " " << g.s[25] << " " << g.s[26]<< "\n";
    for(int mid = 1;mid <= n;mid++){
    	int tr = min(mid - 1, n - mid), tl = 1, tp = 0;
    	while(tl <= tr){
    		int tm = (tl + tr) / 2;
    		if(g.check(mid - tm, mid + tm))
    			tl = tm + 1, tp = tm;
    		else
    			tr = tm - 1;
    	}
    //	cerr << mid << " " << tp << "\n";
    	for(int l = mid - tp, r = mid + tp; l <= r;l++, r--){
    	//	cerr << "was " << " " << l << " " << r << "\n";
    		if(!g.is_were(l, r))
    			break;
    		//break; // UBRAT ------------------------------------------------
    	//	cerr << "was\n";
    	//	cerr << l << " " << r << " " << g.get_cnt(l, r) << "\n";
    		res = max(res, (r - l + 1ll) * g.get_cnt(l, r));
    	}
    }
    //cerr << g.get_cnt(5, 6) << "\n";
    for(int mid = 2;mid <= n;mid++){
    	if(g.s[mid - 1] != g.s[mid - 2])
    		continue;
    	int tr = min(mid - 2, n - mid), tl = 1, tp = 0;
    	while(tl <= tr){
    		int tm = (tl + tr) / 2;
    		if(g.check(mid - 1 - tm, mid + tm))
    			tl = tm + 1, tp = tm;
    		else
    			tr = tm - 1;
    	}
    	for(int l = mid - 1 - tp, r = mid + tp; l <= r;l++, r--){
    		if(!g.is_were(l, r))
    			break;
    	//	cerr << l << " " << r << " " << g.get_cnt(l, r) << "\n";
    		res = max(res, (r - l + 1ll) * g.get_cnt(l, r));
    	}
    }
    cout << res;

    cerr << (clock() - start_f) / CLOCKS_PER_SEC;
}

Subtask #1
8.0 / 8.0

# Verdict Execution time Memory Grader output
1 Correct 9 ms 8576 KB Output is correct
2 Correct 11 ms 8576 KB Output is correct
3 Correct 9 ms 8576 KB Output is correct
4 Correct 10 ms 8576 KB Output is correct
5 Correct 10 ms 8576 KB Output is correct
6 Correct 10 ms 8576 KB Output is correct
7 Correct 9 ms 8576 KB Output is correct
8 Correct 10 ms 8704 KB Output is correct
9 Correct 11 ms 8704 KB Output is correct
10 Correct 10 ms 8704 KB Output is correct
11 Correct 10 ms 8704 KB Output is correct
12 Correct 10 ms 8704 KB Output is correct
13 Correct 10 ms 8704 KB Output is correct
14 Correct 11 ms 8704 KB Output is correct
15 Correct 10 ms 8704 KB Output is correct
16 Correct 9 ms 8704 KB Output is correct
17 Correct 10 ms 8704 KB Output is correct
18 Correct 9 ms 8704 KB Output is correct
19 Correct 9 ms 8704 KB Output is correct
20 Correct 11 ms 8704 KB Output is correct
21 Correct 11 ms 8704 KB Output is correct
22 Correct 11 ms 8704 KB Output is correct
23 Correct 11 ms 8704 KB Output is correct
24 Correct 11 ms 8704 KB Output is correct
25 Correct 11 ms 8704 KB Output is correct
26 Correct 11 ms 8704 KB Output is correct
27 Correct 10 ms 8704 KB Output is correct
28 Correct 11 ms 8704 KB Output is correct
29 Correct 12 ms 8704 KB Output is correct
30 Correct 10 ms 8704 KB Output is correct
31 Correct 10 ms 8704 KB Output is correct
32 Correct 11 ms 8704 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 11 ms 8832 KB Output is correct
2 Correct 11 ms 8832 KB Output is correct
3 Correct 17 ms 8832 KB Output is correct
4 Correct 11 ms 8832 KB Output is correct
5 Correct 12 ms 8832 KB Output is correct
6 Correct 13 ms 8832 KB Output is correct
7 Correct 11 ms 8832 KB Output is correct
8 Correct 11 ms 8832 KB Output is correct
9 Correct 12 ms 8832 KB Output is correct
10 Correct 12 ms 8832 KB Output is correct
11 Correct 11 ms 8832 KB Output is correct
12 Correct 12 ms 8832 KB Output is correct

Subtask #3
24.0 / 24.0

# Verdict Execution time Memory Grader output
1 Correct 33 ms 10252 KB Output is correct
2 Correct 31 ms 10260 KB Output is correct
3 Correct 41 ms 10252 KB Output is correct
4 Correct 39 ms 10252 KB Output is correct
5 Correct 31 ms 10288 KB Output is correct
6 Correct 31 ms 10260 KB Output is correct
7 Correct 31 ms 10252 KB Output is correct
8 Correct 25 ms 9884 KB Output is correct
9 Correct 25 ms 9884 KB Output is correct
10 Correct 31 ms 10124 KB Output is correct

Subtask #4
26.0 / 26.0

# Verdict Execution time Memory Grader output
1 Correct 333 ms 25692 KB Output is correct
2 Correct 317 ms 25564 KB Output is correct
3 Correct 425 ms 25440 KB Output is correct
4 Correct 403 ms 25692 KB Output is correct
5 Correct 364 ms 25568 KB Output is correct
6 Correct 301 ms 24164 KB Output is correct
7 Correct 322 ms 24820 KB Output is correct
8 Correct 238 ms 21084 KB Output is correct
9 Correct 271 ms 22148 KB Output is correct
10 Correct 379 ms 24836 KB Output is correct

Subtask #5
0 / 27.0

# Verdict Execution time Memory Grader output
1 Execution timed out 1090 ms 60952 KB Time limit exceeded
2 Halted 0 ms 0 KB -