Submission #987732

#	Time	Username	Problem	Language	Result	Execution time	Memory
987732		ErJ	Palindromic Partitions (CEOI17_palindromic)	C++17	100 / 100	329 ms	30280 KiB

palindromic

#include<bits/stdc++.h>
    
#define ll long long
#define vi vector<ll>
#define vvi vector<vi>
#define pp pair<ll, ll>
#define inf 1000000000000000
    
    
using namespace std;
    
    
    
string s;
    
bool test(string x, int i, int j){ // all in
    bool is = true;
    for(int k = i; k <= j; k++){
        if(x[k - i] != s[k]){
            is = false;
        }
    }
    return is;
}

ll P = 37;
ll MOD = 1000000007;
vi pref;
vi AKTP;
ll polyHash(ll a, ll b){
    ll ans = pref[b+ 1] - pref[a];
    ans %= MOD;
    if(ans < 0){
        ans += MOD;
    }
    return ans;
}

bool test2(ll a, ll b, ll i, ll j){
    if((polyHash(a, b) * AKTP[i - a]) % MOD == polyHash(i, j)){
        return true;
    }else{
        return false;
    }
}
    
int main(){
    int t;
    cin >> t;
    while(t--){
        cin >> s;
        int n = s.size();
        pref.clear();
        AKTP.clear();
        pref.resize(n + 1);
        pref[0] = 0;
        ll aktP = P;
        AKTP.resize(n + 1);
        AKTP[0] = 1;
        for(int i = 1; i < pref.size(); i++){
            ll val = (ll)s[i - 1] - 96;
            pref[i] = (pref[i - 1] + aktP * val) % MOD;
            AKTP[i] = aktP;
            aktP *= P;
            aktP %= MOD;
        }

        int ans = 0;
        int mid = n/2;
        string akt = "";
        ll from = 0;
        for(int i = 0; i < mid; i++){
            akt += s[i];
            if(test2(from, i, n - 1 - i,  n - 1 - (i - akt.size() + 1))){
                ans += 2;
                from = i + 1;
                akt = "";
            }
        }
        if(n %2 == 1) akt += "a";
        if(akt != ""){
            ans++;
        }
        cout << ans << endl;
    }
}

Compilation message (stderr)

palindromic.cpp: In function 'int main()':
palindromic.cpp:60:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   60 |         for(int i = 1; i < pref.size(); i++){
      |                        ~~^~~~~~~~~~~~~

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