Submission #1272684

#	Time	Username	Problem	Language	Result	Execution time	Memory
1272684		iamsazidh	Palindromic Partitions (CEOI17_palindromic)	C++20	100 / 100	478 ms	34572 KiB

palindromic

//ᴇᴀᴄʜ ᴘᴇʀꜱᴏɴ ᴡɪʟʟ ᴏɴʟʏ ʜᴀᴠᴇ ᴡʜᴀᴛ ᴛʜᴇʏ ᴇɴᴅᴇᴀᴠᴏᴜʀᴇᴅ ᴛᴏᴡᴀʀᴅꜱ [53:39]
//Author: Sazid Hasan
#include <bits/stdc++.h>
using namespace std;

typedef long long              ll;
typedef double                 dl;
typedef vector<int>            vi;
typedef vector<vector<int>>    vii;
typedef vector<ll>             vl;
typedef vector<bool>           vb;
typedef pair<int,int>         pii;
typedef pair<ll, ll>          pll;

#define ff                first
#define ss                second
#define all(a)            a.begin(),a.end()
#define gcd(a,b)          __gcd(a,b)
#define lcm(a,b)          (a*(b/gcd(a,b)))
#define file();           freopen("input.txt", "r", stdin);freopen("output.txt", "w", stdout);
#define flush             fflush(stdout);
#define spc               " "

#ifdef ONLINE_JUDGE
    #define debarr(array)
    #define deb(x)
    #define del
    #define debug(...)
#else
    #define debarr(array)  for(int w = 0; w < array.size(); w++) cerr << #array << "-" << w << " = " << array[w] << endl;
    #define deb(x)         cerr << #x << " = " << x << endl;
    #define del cerr << '\n';
    #define debug(...) _debug(#__VA_ARGS__, __VA_ARGS__);
    
    template <class X, class Y>
    ostream& operator<<(ostream& os, const pair<X, Y>& p) {
        return os << "(" << p.first << ", " << p.second << ")";
    }
    
    template <class Ch, class Tr, class Container>
    basic_ostream<Ch, Tr>& operator<<(basic_ostream<Ch, Tr>& os, const Container& x) {
        int i = 0, n = distance(x.begin(), x.end());
        os << "{ ";
        for (const auto& y : x)
            os << y << (++i < n ? ", " : "");
        return os << " }";
    }
    
    template <typename... Args>
    void _debug(const char* names, Args&&... args) {
        string_view s(names);
        cerr << "{ ";
        size_t i = 0, cnt = 0, n = sizeof...(args);
    
        auto next = [&]() {
            while (i < s.size() && (s[i] == ' ' || s[i] == ',')) ++i;
            size_t st = i;
            while (i < s.size() && s[i] != ',') ++i;
            return s.substr(st, i - st);
        };
    
        ((cerr << next() << ": " << args << (++cnt < n ? ", " : "")), ...);
        cerr << " }" << '\n';
    }
#endif


const double PI =         acos(-1);
const int MOD =           1000000007;
const int inf =           (2147483647);
const double EPS =        1e-6;
const int MAXN =          1e5+10;

class   Hashing{
    private:
        vl hash; ll A, B; int n;
        vl P;
    public:
        Hashing(int _n, ll _A, ll _B, string &s){
            A = _A;
            B = _B;
            n = _n;
            hash.resize(n);
            P.resize(n+3, 1);
            P[1] = A;
            hash[0] = s[0];
            for(int i = 1; i < n; i++){
                hash[i] = (hash[i-1]*A+s[i])%B;
            }
            for(int i = 2; i <= n; i++) P[i] = (P[i-1]*A)%B;
        }
        ll str(int l, int r){
            if(l==0) return hash[r];
            return (hash[r]-((hash[l-1]*P[r-l+1])%B)+B)%B;
        }
};

bool solve(){
    string s; cin >> s;
    int n = s.size();
    int cnt = 0;
    int l1 = 0, r1 = 0, l2 = n-1, r2 = n-1;
    Hashing A(n, 37, MOD, s);
    Hashing B(n, 23, MOD+2, s);
    while(r1<l2){
        if(A.str(l1, r1)==A.str(l2, r2) && B.str(l1, r1)==B.str(l2, r2)){
            cnt += 2;
            if(r1+1==l2){
                cout << cnt << endl; return 0;
            }
            l1 = r1 = r1+1;
            l2 = r2 = l2-1;
        }else{
            r1++, l2--;
        }
    }
    cout << ++cnt << endl;

    return 1;
}

int main(){
    ios::sync_with_stdio(false); cin.tie(nullptr);
    int testcase = 1;
    cin >> testcase;
    for(int tc = 1; tc <= testcase; tc++){
        // cerr << "TESTCASE - " << tc << endl;
        solve();
        //cout << (solve() ? "YES" : "NO") << '\n';
        cerr << endl;
    }

    return 0;
}

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