Submission #551614

#	Time	Username	Problem	Language	Result	Execution time	Memory
551614		hoanghq2004	Palindromes (APIO14_palindrome)	C++14	100 / 100	24 ms	36272 KiB

palindrome

#include <bits/stdc++.h>
#pragma GCC optimization ("O3")
#pragma GCC optimization ("unroll-loops")
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace __gnu_pbds;
using namespace std;

template <typename T>
using ordered_set = tree <T, null_type, less <T>, rb_tree_tag, tree_order_statistics_node_update>;

const int N = 3e5 + 10;

int nNode, suff;
string s;

struct node {
    int nxt[26];
    int len, link;
} Tree[N];

void init() {
    nNode = 1, suff = 1;
    Tree[0].len = -1;
    Tree[1].len = 0;
}

void add(int i) {
    int cur = suff;
    while (1) {
        int curlen = Tree[cur].len;
        if (s[i] == s[i - curlen - 1]) break;
        cur = Tree[cur].link;
    }
    if (Tree[cur].nxt[s[i] - 'a']) {
        suff = Tree[cur].nxt[s[i] - 'a'];
        return;
    }
    suff = ++nNode;
    Tree[cur].nxt[s[i] - 'a'] = suff;
    Tree[suff].len = Tree[cur].len + 2;
    if (Tree[suff].len == 1) {
        Tree[suff].link = 1;
        return;
    }
    while (1) {
        cur = Tree[cur].link;
        int curlen = Tree[cur].len;
        if (s[i] == s[i - curlen - 1]) break;
    }
    Tree[suff].link = Tree[cur].nxt[s[i] - 'a'];
}

long long cnt[N];

int main() {
    ios :: sync_with_stdio(0); cin.tie(0);
    cin >> s;
    init();
    for (int i = 0; i < s.size(); ++i) add(i), ++cnt[suff];
    for (int i = nNode; i >= 0; --i)
        cnt[Tree[i].link] += cnt[i];
    long long ans = 0;
    for (int i = 1; i <= nNode; ++i) ans = max(ans, cnt[i] * Tree[i].len);
    cout << ans;
}

Compilation message (stderr)

palindrome.cpp:2: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    2 | #pragma GCC optimization ("O3")
      | 
palindrome.cpp:3: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    3 | #pragma GCC optimization ("unroll-loops")
      | 
palindrome.cpp: In function 'int main()':
palindrome.cpp:61:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   61 |     for (int i = 0; i < s.size(); ++i) add(i), ++cnt[suff];
      |                     ~~^~~~~~~~~~

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