제출 #795325

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
795325		cig32	Palindromic Partitions (CEOI17_palindromic)	C++17	100 / 100	380 ms	35552 KiB

palindromic

#include "bits/stdc++.h"
using namespace std;
#define int long long
const int MAXN = 3e5 + 10;
const int MOD = 1e9 + 7;
mt19937_64 rng((int)std::chrono::steady_clock::now().time_since_epoch().count());
int rnd(int x, int y) {
  int u = uniform_int_distribution<int>(x, y)(rng); return u;
}
int bm(int b, int p) {
  if(p==0) return 1 % MOD;
  int r = bm(b, p >> 1);
  if(p&1) return (((r*r) % MOD) * b) % MOD;
  return (r*r) % MOD;
}
int inv(int b) { 
  return bm(b, MOD-2);
}
int fastlog(int x) {
  return (x == 0 ? -1 : 64 - __builtin_clzll(x) - 1);
}
void printcase(int i) { cout << "Case #" << i << ": "; }

//untested

struct hash_string {
  const int fac = 2017;
  const int MOD = 1734232211; // prime!
  vector<int> pau, ps; // all indices 0-based
  int n;
  void init(string s) {
    n = s.size();
    pau.push_back(1);
    for(int i=1; i<=n; i++) {
      pau.push_back((pau[i-1] * fac) % MOD);
    }
    ps.push_back(s[0]);
    for(int i=1; i<n; i++) {
      ps.push_back((ps[i-1] * fac + s[i]) % MOD);
    }
  }
  int eval(int l, int r) {
    return (ps[r] - (l == 0 ? 0 : (ps[l-1] * pau[r-l+1]) % MOD) + MOD) % MOD;
  }
};
void solve(int tc) {
  hash_string hst;
  string bruh;
  cin >> bruh;
  hst.init(bruh);
  int l = 0, r = bruh.size() - 1;
  int c = 0, ans = 1;
  while(l <= r) {
    bool bad = 1;
    for(int i=1; i<=(r-l+1)/2; i++) {
      if(hst.eval(l, l+i-1) == hst.eval(r-i+1, r)) {
        c += 2, l += i, r -= i;
        ans = max(ans, c + (l <= r));
        bad = 0;
        break;
      }
    }
    if(bad) break;
  }
  cout << ans << "\n";
}
int32_t main() {
  ios::sync_with_stdio(0); cin.tie(0);
  int t = 1; cin >> t;
  for(int i=1; i<=t; i++) solve(i);
}
// 勿忘初衷

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