Submission #1226111

#	Time	Username	Problem	Language	Result	Execution time	Memory
1226111		theiulius	Palindromic Partitions (CEOI17_palindromic)	C++20	100 / 100	102 ms	18924 KiB

palindromic

#include<bits/stdc++.h>
using namespace std;
#define int long long
#define ff first
#define ss second
#define pb push_back
// #define endl "\n"
const int MOD = 1e9 + 7, N = 1e6 + 6;
int n;

main(){
    /*ifstream cin(".in");
    ofstream cout(".out");*/
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    
    int myp[N] = {1};
    for (int i = 1; i < N; i++){
        myp[i] = (myp[i - 1] * 31) % MOD;
    }
    
    cin >> n;
    for (int k = 0; k < n; k++){
        string s;
        cin >> s;
        
        int pre[s.size()] = {};
        pre[0] = s[0] - 'a';
        int num = 1;
        for (int i = 1; i < s.size(); i++){
            num *= 31;
            num %= MOD;
            // cout << ((s[i] - 'a') * num) << endl;
            pre[i] = (pre[i - 1] + (s[i] - 'a') * num) % MOD;
        }
        
        int last = 0, ans = 0;
        for (int i = 0; i < s.size() / 2; i++){
            int a = pre[i];
            if (last){
                a -= pre[last - 1] - MOD;
                a %= MOD;
            }
            int b = (pre[s.size() - 1 - last] - pre[s.size() - 2 - i] + MOD) % MOD;
            
            int h = s.size() - 1 - last - i;
            a *= myp[h];
            a %= MOD;
            
            if (a == b){
                ans++;
                last = i + 1;
            }
        }
        ans *= 2;
        if (s.size() % 2 || last != s.size() / 2){
            ans++;
        }
        cout << ans << endl;
    }
    
}

Compilation message (stderr)

palindromic.cpp:11:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   11 | main(){
      | ^~~~

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