Submission #731162

#	Time	Username	Problem	Language	Result	Execution time	Memory
731162		Alihan_8	Palindromes (APIO14_palindrome)	C++17	23 / 100	1090 ms	43072 KiB

palindrome

#include <bits/stdc++.h>

using namespace std;

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

bool chmin(int &x, int y){
    bool flag = false;
    if ( x > y ){
        x = y; flag |= true;
    }
    return flag;
}

bool chmax(int &x, int y){
    bool flag = false;
    if ( x < y ){
        x = y; flag |= true;
    }
    return flag;
}

struct Hash{
    const int Mod = 1e9 + 7, P = 29;
    int n;
    vector <int> p, pw;
    Hash(string s) : n((int)s.size()), p(n + 1), pw(n + 1, 1) {
        for ( int i = 0; i < n; i++ ){
            pw[i + 1] = pw[i] * P % Mod;
            p[i + 1] = (p[i] * P + (s[i] - 'a' + 1)) % Mod;
        }
    }
    int get(int l, int r){
        int v = p[r + 1] - (p[l] * pw[r - l + 1]) % Mod;
        return v < 0 ? Mod + v : v;
    }
};

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

    string s; cin >> s;
    int n = (int)s.size();
    map <int,int> mp;
    Hash u(s);
    for ( int i = 0; i < n; i++ ){
        string c;
        for ( int j = i; j < n; j++ ){
            mp[u.get(i, j)]++;
        }
    }
    int Mx = 0;
    for ( int i = 0; i < n; i++ ){
        chmax(Mx, mp[u.get(i, i)]);
        for ( int j = i - 1; j >= 0; j-- ){
            int l = j, r = (i - j) + i;
            if ( r >= n or s[l] != s[r] ) break;
            chmax(Mx, mp[u.get(l, r)] * (r - l + 1));
        }
        if ( i + 1 == n or s[i + 1] != s[i] ) continue;
        chmax(Mx, mp[u.get(i, i+1)] * 2);
        for ( int j = i - 1; j >= 0; j-- ){
            int l = j, r = (i - j) + (i + 1);
            if ( r >= n or s[j] != s[r] ) break;
            chmax(Mx, mp[u.get(l, r)] * (r - l + 1));
        }
    }
    cout << Mx;

    cout << '\n';
}

• Subtask 1: 8 / 8
• Subtask 2: 15 / 15
• Subtask 3: 0 / 24
• Subtask 4: 0 / 26
• Subtask 5: 0 / 27