Submission #84497

#	Time	Username	Problem	Language	Result	Execution time	Memory
84497		popovicirobert	Palindromes (APIO14_palindrome)	C++14	23 / 100	384 ms	49028 KiB

palindrome

#include <bits/stdc++.h>
#define lsb(x) (x & (-x))
#define ll long long
#define ull unsigned long long
// 217
// 44

using namespace std;

const int MAXN = (int) 3e5;
const int B = 57;

char str[MAXN + 1];

ull pw[MAXN + 1], hsh[MAXN + 1];

inline ull get_hsh(int l, int r) {
    return hsh[r] - hsh[l - 1] * pw[r - l + 1];
}

int len[2 * MAXN + 5];

inline void manacher(int n) {
    vector <char> aux(2 * n + 5);
    int i, sz = 0;
    for(i = 1; i <= n; i++) {
        aux[++sz] = '*';
        aux[++sz] = str[i];
    }
    aux[++sz] = '*';
    int p = 0;
    for(i = 1; i <= sz; i++) {
        if(p + len[p] >= i) {
            len[i] = min(len[2 * p - i], p + len[p] - i);
        }
        while(i - len[i] > 0 && i + len[i] <= sz && aux[i - len[i]] == aux[i + len[i]]) {
            len[i]++;
        }
        if(i + len[i] > p + len[p]) {
            p = i;
        }
    }
}

unordered_map <ull, int> mp;

struct Trie {
    vector <int> sons;
    ll lvl, sz;
};

vector <Trie> v;
ll ans = 0;

void dfs(int nod) {
    for(auto it : v[nod].sons) {
        dfs(it);
        v[nod].sz += v[it].sz;
    }
    ans = max(ans, 1LL * v[nod].lvl * v[nod].sz);
}

int main() {
    //ifstream cin("B.in");
    //ofstream cout("B.out");
    int i;
    ios::sync_with_stdio(false);
    cin >> str + 1;
    int n = strlen(str + 1);
    manacher(n);
    pw[0] = 1;
    for(i = 1; i <= n; i++) {
        pw[i] = pw[i - 1] * B;
        hsh[i] = hsh[i - 1] * B + str[i] - 'a' + 1;
    }
    int id = 1;
    v.resize(2);
    for(i = 2; i <= 2 * n; i++) {
        int last = 0, j = 0;
        bool ok = 0;
        for(j = len[i] / 2; j >= 1; j--) {
            ull cur = get_hsh(i / 2 - j + 1, i / 2 + j - (1 - i % 2));
            int l = 2 * j - (1 - i % 2);
            ok = 0;
            if(mp[cur] == 0) {
                ok = 1;
                mp[cur] = ++id;
                Trie aux;
                aux.lvl = l;
                aux.sz = 0;
                v.push_back(aux);
            }
            if(last != 0) {
                v[mp[cur]].sons.push_back(last);
            }
            else {
                v[mp[cur]].sz++;
            }
            last = mp[cur];
            if(!ok) {
                break;
            }
        }
        if(ok == 1) {
            v[1].sons.push_back(last);
        }
    }
    dfs(1);
    cout << ans;
    //cin.close();
    //cout.close();
    return 0;
}

Compilation message (stderr)

palindrome.cpp: In function 'int main()':
palindrome.cpp:68:16: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
     cin >> str + 1;
            ~~~~^~~

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