제출 #921426

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
921426		AVIJIT_BISWAS	회문 (APIO14_palindrome)	C++14	0 / 100	18 ms	36008 KiB

palindrome

#include <bits/stdc++.h>
using namespace std;
#define ll long long

struct PalindromicTree {
  struct node {
    int nxt[26], len, link, occ;
  };
  string s;
  vector<node> t;
  int sz, last;
  PalindromicTree() {}
  PalindromicTree(string _s) {
    s = _s;
    int n = s.size();
    t.clear();
    t.resize(n + 9);
    sz = 2, last = 2;
    t[1].len = -1, t[1].link = 1;
    t[2].len = 0, t[2].link = 1;
  }
  int extend(int pos) { // returns 1 if it creates a new palindrome
    int cur = last, curlen = 0;
    int ch = s[pos] - 'a';
    while (1) {
      curlen = t[cur].len;
      if (pos - 1 - curlen >= 0 && s[pos - 1 - curlen] == s[pos]) break;
      cur = t[cur].link;
    }
    if (t[cur].nxt[ch]) {
      last = t[cur].nxt[ch];
      return 0;
    }
    sz++;
    last = sz;
    t[sz].len = t[cur].len + 2;
    t[cur].nxt[ch] = sz;

    ++t[last].occ;

    if (t[sz].len == 1) {
      t[sz].link = 2;
      return 1;
    }
    while (1) {
      cur = t[cur].link;
      curlen = t[cur].len;
      if (pos - 1 - curlen >= 0 && s[pos - 1 - curlen] == s[pos]) {
        t[sz].link = t[cur].nxt[ch];
        break;
      }
    }


    return 1;
  }
}T;


void solve() {
  string s; cin >> s;
  T = PalindromicTree(s);
  int n = s.size();

  for(int i = 0; i < n; i++){
    T.extend(i);
  }


  ll ans = 0;
  for(int i = T.sz; i > 2; i--) {
    T.t[T.t[i].link].occ  += T.t[i].occ;
    ans = max(ans, 1ll * T.t[i].occ * T.t[i].len);
  }

  cout << ans << '\n';

}

int32_t main() {
    ios_base::sync_with_stdio(false); cin.tie(nullptr);int t = 1;
    
    #ifndef ONLINE_JUDGE
    freopen("output.txt", "w", stderr);
    #endif

    // cin >> t;

    for(int i = 1; i <= t; i++){
    //cout << "-----Case:" << i << "-----\n";
        solve();
    }

    return 0;
}

컴파일 시 표준 에러 (stderr) 메시지

palindrome.cpp: In function 'int32_t main()':
palindrome.cpp:84:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   84 |     freopen("output.txt", "w", stderr);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

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