Submission #627075

#	Time	Username	Problem	Language	Result	Execution time	Memory
627075		a_aguilo	Palindromic Partitions (CEOI17_palindromic)	C++17	0 / 100	21 ms	15956 KiB

palindromic

#include<bits/stdc++.h>

using namespace std;

const int p = 73;
const long long m = 1e11 + 3;

long long int hashes[1000000];
long long int powers[1000000];
int n;

long long getHash(int start, int ending){
    if(ending == 0) return hashes[0];
    if(start == n-1) return ((hashes[n-1] - (hashes[n - 2] * p)%m)%m + m)%m;
    if(start == 0) return hashes[ending];
    return ((hashes[ending] - (hashes[start - 1] * powers[ending - start+1])%m)%m + m)%m;
}

int main(){
    int t;
    string s;
    cin >> t;
    while(t--){
        cin >> s;
        n = s.size();
        memset(hashes, 0, sizeof(hashes));
        memset(powers, 0, sizeof(powers));
        hashes[0] = s[0]-'a'+1;
        powers[0] = 1;
        for(int i = 1; i < s.size(); ++i){
            hashes[i] = (((__int128)hashes[i-1]*p)%m + (s[i]-'a' + 1))%m;
            powers[i] = ((__int128)powers[i-1]*p)%m;
        }
        int ans = 1;
        int MaxLeft = -1;
        int MaxRight = s.size();
        int left = 0; int right = s.size()-1;
        while(left < right){
            if(getHash(MaxLeft+1, left) == getHash(right, MaxRight-1)){
                ans+=2;
                MaxLeft = left;
                MaxRight = right;
            }
            left++;
            right--;
        }
        if(MaxLeft+1 == MaxRight)ans--;
        cout << ans << endl;;
    }
    return 0;
}

Compilation message (stderr)

palindromic.cpp: In function 'int main()':
palindromic.cpp:30:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   30 |         for(int i = 1; i < s.size(); ++i){
      |                        ~~^~~~~~~~~~

• Subtask 1: 0 / 15
• Subtask 2: 0 / 20
• Subtask 3: 0 / 25
• Subtask 4: 0 / 40