Submission #915775

#	Time	Username	Problem	Language	Result	Execution time	Memory
915775		Nelt	Palindromic Partitions (CEOI17_palindromic)	C++17	100 / 100	48 ms	19000 KiB

palindromic

#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx,avx2,fma,popcnt")

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

/* DEFINES */
#define S second
#define F first
#define ll long long
#define ull unsigned long long
#define ld long double
#define npos ULLONG_MAX
#define INF LLONG_MAX
#define vv(a) vector<a>
#define ss(a) set<a>
#define pp(a, b) pair<a, b>
#define mm(a, b) map<a, b>
#define qq(a) queue<a>
#define pq(a) priority_queue<a>
#define ump(a, b) unordered_map<a, b>
#define ANDROID                   \
    ios_base::sync_with_stdio(0); \
    cin.tie(0);                   \
    cout.tie(0);
#define allc(a) begin(a), end(a)
#define all(a) a, a + sizeof(a) / sizeof(a[0])
#define elif else if
#define endl "\n"
#define pb push_back
#define ins insert
#define logi __lg
#define sqrt sqrtl
#define mpr make_pair
using namespace std;
using namespace __cxx11;
using namespace __gnu_pbds;
typedef char chr;
typedef basic_string<chr> str;
template <typename T, typename key = less<T>>
using ordered_set = tree<T, null_type, key, rb_tree_tag, tree_order_statistics_node_update>;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const ll p = 37;
void solve()
{
    str s;
    cin >> s;
    ll n = s.size();
    s = ' ' + s;
    ll pref[n + 1], pw[n + 1];
    pw[0] = 1;
    pref[0] = 0;
    for (ll i = 1; i <= n; i++)
        s[i] -= 'a' - 1, pw[i] = pw[i - 1] * p, pref[i] = pref[i - 1] + s[i] * pw[i];
    auto sum = [&](ll l, ll r)
    {
        return pref[r] - pref[l - 1];
    };
    ll l = 1, r = n, ans = 0;
    while (l <= r)
    {
        ll curl = l, curr = r;
        while (sum(l, curl) * pw[curr - l] != sum(curr, r))
            curl++, curr--;
        ans += curl == r ? 1 : 2;
        l = curl + 1;
        r = curr - 1;
    }
    cout << ans << endl;
}
/*

*/
int main()
{
    ANDROID
    // precomp();
    ll t = 1;
    cin >> t;
    for (ll i = 1; i <= t; i++)
        // cout << "Case #" << i << ": ",
        solve();
    cerr << "\nTime elapsed : " << clock() * 1000.0 / CLOCKS_PER_SEC << " ms\n";
}

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