Submission #147272

#	Time	Username	Problem	Language	Result	Execution time	Memory
147272		claudy	Palindromic Partitions (CEOI17_palindromic)	C++14	100 / 100	442 ms	36052 KiB

palindromic

//# pragma GCC optimize("Ofast,no-stack-protector")
//# pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native")
# pragma GCC optimize("Ofast")
# pragma GCC optimization ("unroll-loops")
# include "bits/stdc++.h"
/*
# include <ext/pb_ds/tree_policy.hpp>
# include <ext/pb_ds/assoc_container.hpp>
# include <ext/rope>
*/
std::pair<int,int> DR[] = {{-1,0},{0,1},{1,0},{0,-1},{-1,1},{-1,-1},{1,1},{1,-1}};
# define ll long long
# define clock (clock() * 1000.0 / CLOCKS_PER_SEC)
# define rc(s) return cout << s,0
# define rcg(s) cout << s;exit(0)
# define _ ios_base::sync_with_stdio(false);cin.tie(0);cerr.tie(0);cout.tie(0);
# define db(x) cerr << #x << " = " << x << '\n'
# define pb push_back
# define mp make_pair
# define all(s) s.begin(),s.end()
# define sz(x) (int)((x).size())
# define int ll
using namespace std;

/*
using namespace __gnu_pbds;
using namespace __gnu_cxx;
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;
Tree<int>tr;
*/

// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# define LOCAL
# define sim template < class c
# define ris return * this
# define dor > debug & operator <<
# define eni(x) sim > typename \
enable_if<sizeof dud<c>(0) x 1, debug&>::type operator<<(c i) {
sim > struct rge { c b, e; };
sim > rge<c> range(c i, c j) { return rge<c>{i, j}; }
sim > auto dud(c* x) -> decltype(cerr << *x, 0);
sim > char dud(...);
struct debug {
#ifdef LOCAL
~debug() { cerr << endl; }
eni(!=) cerr << boolalpha << i; ris; }
eni(==) ris << range(begin(i), end(i)); }
sim, class b dor(pair < b, c > d) {
ris << "(" << d.first << ", " << d.second << ")";
}
sim dor(rge<c> d) {
*this << "[";
for (auto it = d.b; it != d.e; ++it)
*this << ", " + 2 * (it == d.b) << *it;
ris << "]";
}
#else
sim dor(const c&) { ris; }
#endif
};
#define show(...) " [" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "] "
int gcd(int a, int b)
{
if(b) return gcd(b,a%b);
return a;
}mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

// 6:35

const int P = 31;
const int mod = 1e9 + 9;

int t,p[1 << 20],inv[1 << 20],pref[1 << 20],suff[1 << 20];

int mypow(int x,int p)
{
	int ans = 1;
	for(int i = 0;(1LL << i) <= p;i++){
		if(p & (1LL << i)){
			ans *= x;
			ans %= mod;
		}
		x *= x;
		x %= mod;
	}
	return ans;
}

int32_t main(){_
	//freopen("input","r",stdin);
	cin >> t;
	p[0] = 1;
	for(int i = 1;i <= 1000000;i++) p[i] = (P * p[i - 1]) % mod;
	for(int i = 0;i <= 1000000;i++) inv[i] = mypow(p[i],mod - 2);
	while(t--){
		string s;
		cin >> s;
		int n = sz(s);
		for(int i = 0;i < n;i++){
			int x = 0;
			if(i > 0) x = pref[i - 1];
			pref[i] = (x + (s[i] - 'a') * p[i]) % mod;
		}
		for(int i = n - 1;i >= 0;i--){
			int x = 0;
			if(i < n - 1) x = suff[i + 1];
			suff[i] = ((x * P) % mod + s[i] - 'a') % mod;
		}
		int l = 0;
		int r = n - 1;
		int ans = 0;
		while(l <= r){
			bool ok = 0;
			for(int i = l;i < r - i + l;i++){
				if(ok) break;
				int a = ((pref[i] - (l ? pref[l - 1] : 0)) * inv[l]) % mod;
				if(a < 0) a += mod;
				int x = r - i + l;
				int b = (suff[x] - suff[r + 1] * p[r + 1 - x]) % mod;
				if(b < 0) b += mod;
				if(a == b){
					ok = 1;
					r = x - 1;
					l = i + 1;
				}
			}
			if(!ok){
				ans++;
				break;
			}
			else ans += 2;
		}
		memset(pref,0,sizeof(pref));
		memset(suff,0,sizeof(suff));
		cout << ans << '\n';
	}
	return 0;
}

Compilation message (stderr)

palindromic.cpp:4:0: warning: ignoring #pragma GCC optimization [-Wunknown-pragmas]
 # pragma GCC optimization ("unroll-loops")

• Subtask 1: 15 / 15
• Subtask 2: 20 / 20
• Subtask 3: 25 / 25
• Subtask 4: 40 / 40