Submission #1312570

#	Time	Username	Problem	Language	Result	Execution time	Memory
1312570		sebokx	Palindromic Partitions (CEOI17_palindromic)	C++20	100 / 100	54 ms	5420 KiB

palindromic

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
#define st first
#define nd second 
#define vi vector<int>
#define vll vector<long long>
#define pii pair<int, int>
#define pll pair<long long, long long>
#define pb push_back
#define mp make_pair
#define all(x) (x).begin(), (x).end()
#define len(x) (int)(x).size()
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
mt19937_64 rng64(chrono::high_resolution_clock::now().time_since_epoch().count());
inline int rand(int l,int r){return uniform_int_distribution<int>(l, r)(rng);}
inline ll rand(ll l,ll r){return uniform_int_distribution<ll>(l, r)(rng64);}
template <typename T, typename H>
ostream& operator<<(ostream& os, pair<T, H> p){
	return os << "(" << p.st << ", " << p.nd << ")";
}
template <typename T>
ostream& operator<<(ostream& os, vector<T> v){
	os << "{";
	for(int i = 0; i < v.size(); i++){
		if(i != 0) os << ", ";
		os << v[i];
	}
	os << "}";
	return os;
}
#ifdef DEBUG
#define fastio()
#define debug(x...) cerr << "[" << #x << "]: ", [](auto... $) {((cerr << $ << ", "), ...); }(x), cerr << '\n'
#else
#define fastio() ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL)
#define debug(x...)
#endif

constexpr int P = 271;
constexpr int MOD = 1e9+7;
constexpr int N = 1e6+7;
string s;

int pows[N];

void solve(){
	cin >> s;

	int n = len(s);

	int ans = 0;

	int left = 0;
	int right = n-1;
	int sajz = 0;

	int lh = 0;
	int rh = 0;

	while(left < right){
		// update lh
		lh = ((ll)lh * (ll)P) % MOD;
		lh = ((ll)lh + (ll)s[left]) % MOD;

		// update rh
		int to_add = ((ll)pows[sajz] * (ll)s[right]) % MOD;
		rh = ((ll)rh + (ll)to_add) % MOD;

		sajz++;

		if(lh == rh){
			ans += 2;
			lh = 0;
			rh = 0;
			sajz = 0;
		}

		left++;
		right--;
	}

	if(sajz != 0 || left == right) ans++;

	cout << ans << '\n';
}

int32_t main(){
    fastio();

	pows[0] = 1;
	for(int i = 1; i < N; i++) pows[i] = ((ll)pows[i-1] * (ll)P) % MOD;

    int tt = 1;
    cin >> tt;
    while(tt--) solve();

    return 0;
}

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