Submission #939111

#	Time	Username	Problem	Language	Result	Execution time	Memory
939111		vjudge1	Palindromic Partitions (CEOI17_palindromic)	C++17	100 / 100	261 ms	35260 KiB

palindromic

#include <bits/stdc++.h>

using namespace std;

#define all(x) x.begin(), x.end()
#define ar array
#define pb push_back
#define ln '\n'
#define int long long

using i64 = long long;

template <class F, class _S>
bool chmin(F &u, const _S &v){
    bool flag = false;
    if ( u > v ){
        u = v; flag |= true;
    }
    return flag;
}

template <class F, class _S>
bool chmax(F &u, const _S &v){
    bool flag = false;
    if ( u < v ){
        u = v; flag |= true;
    }
    return flag;
}

struct Hash{
    vector <int> p, pw;
    const int P = 31;
    // 0 - indexed
    string s;
    int n, Mod;
    Hash(int Mod) : Mod(Mod) {}
    void ins(string _s){
        s = _s;
        n = (int)s.size();
        p.resize(n + 1); pw.pb(1);
        while ( (int)pw.size() <= n ){
            pw.pb(pw.back() * P % Mod);
        }
        for ( int i = 0; i < n; i++ ){
            int f = s[i] - 'a' + 1; // *appropriate subtraction
            p[i + 1] = (p[i] * P + f) % Mod;
        }
    }
    int get(int l, int r){
        int ans = (p[r + 1] - p[l] * pw[r - l + 1]) % Mod;
        if ( ans < 0 ) ans += Mod;
        return ans;
    }
};

void solve(){
    string s; cin >> s;
    Hash h(998244353);
    h.ins(s);
    int l = 0, r = (int)s.size() - 1, ans = 0;
    while ( l <= r ){
        if ( l == r ){
            ans++;
            break;
        }
        int a = l, b = r;
        while ( a < b && h.get(l, a) != h.get(b, r) ){
            a++, b--;
        }
        if ( a >= b ){
            ans++;
            break;
        }
        ans += 2;
        l = a + 1, r = b - 1;
    }
    cout << ans << ln;
}

signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int t; cin >> t;
    while ( t-- ){
        solve();
    }

    cout << '\n';
}

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