Submission #916429

#	Time	Username	Problem	Language	Result	Execution time	Memory
916429		amin_2008	Palindromic Partitions (CEOI17_palindromic)	C++17	100 / 100	165 ms	19840 KiB

palindromic

#pragma GCC optimize ("O3")
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx,avx2,fma")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

// author: amin_2008

typedef long long ll;

#define pb push_back
#define ins insert
#define ts to_string
#define sz(x) (int)(x).size()
#define mp make_pair
#define F first
#define S second
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
#define lb lower_bound
#define ub upper_bound
#define ld long double
#define endl '\n'
#define int ll

using namespace std;
using namespace __gnu_pbds;
using namespace __cxx11;
using pii = pair<int, int>;
using vi = vector<int>;
using vs = vector<string>;
using vpii = vector<pii>;
using vb = vector<bool>;
using vc = vector<char>;
using vvi = vector<vi>;

template <typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
#define debug(x) cerr << (#x) << ": " << x << endl

const int MOD = 998244353;
const int mod = 1e9 + 7;
const int inf = 1e18;
const int sz = 1e6 + 5;
const int N = 1e3;
const int lg = 18;
const int P = 31;

int a[sz];
int pw[sz];
int h[sz];

int get_hash(int l, int r)
{
    return (h[r + 1] - (h[l] * pw[r - l + 1]) % mod + mod) % mod;
}

void solve()
{
    pw[0] = 1;
    for(int i = 1; i < sz; i++) pw[i] = ( pw[i - 1] * P ) % mod;
    string s;
    cin >> s;
    int n = sz(s);
    h[0] = 1;
    for(int i = 0; i < n; i++) h[i + 1] = ( ( h[i] * P ) % mod + s[i] ) % mod;
    int res = 1;
    for(int i = 0; i < ( n >> 1 ); i++)
    {
        int j = i;
        int l = n - i - 1;
        int r = n - i - 1;
        for(; j < ( n >> 1 ); j++, l--)
        {
            if ( get_hash(i, j) == get_hash(l, r) )
            {
                res += 2;
                if ( !( n % 2 ) and j == ( n >> 1 ) - 1 ) res--;
                break;
            }
        }
        i = j;
    }
    cout << res << endl;
}

signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    //precompute();
    int t = 1;
    cin >> t;
    for(int i = 1; i <= t; i++) solve();
}

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