Submission #861393

#	Time	Username	Problem	Language	Result	Execution time	Memory
861393		Vanilla	Palindromic Partitions (CEOI17_palindromic)	C++17	100 / 100	119 ms	35236 KiB

palindromic

#include <bits/stdc++.h>
#include <fstream>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
template<class T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
struct custom_hash {static uint64_t splitmix64(uint64_t x) {x += 0x9e3779b97f4a7c15;x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;x = (x ^ (x >> 27)) * 0x94d049bb133111eb;return x ^ (x >> 31);}size_t operator()(uint64_t x) const {static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();return splitmix64(x + FIXED_RANDOM);}};
// string __fname = ""; ifstream in (__fname + ".in"); ofstream out (__fname + ".out"); 
// #define cin in 
// #define cout out
#define int64 long long
#define uint64 unsigned long long
#define x first
#define y second
#define pb push_back
#define pii pair <int, int> 
#define pii64 pair <int64, int64>
#define db(x) cout << "> " << #x << ": " << (x) << "\n"
#define qr queries()
#define yn(x) if (x) {ctn("Yes");}else {ctn("No");}
void solve(int);
void queries(){int n;cin >> n;for (int i = 1; i <= n; i++) solve(i);}
template<class T>T ceildiv(T a, T b) {return (a + b - 1) / b;}
template<class T>T gcd (T a, T b){return (b ? gcd(b, a % b): a);}
template<class T>T lcm (T a, T b){return a * b / gcd(a, b);}
// // // // // // // // // // // // // // // // // // // // // // 
/*                  TEMPLATE - VANILLA                         */
// // // // // // // // // // // // // // // // // // // // // //
const int ddx[] = {-1, -1, 0, 1, 1, 1, 0, -1};
const int ddy[] = {0, 1, 1, 1, 0, -1, -1, -1};
const int dx[] = {-1, 0, 1, 0};
const int dy[] = {0, 1, 0, -1};
const double pi = 3.14159265359;
const double eps = 1e-6;
const int64 hash_inv = 940594066;
const int64 hash_p = 101;
const int64 mod = 1e9 + 7;
const int maxn = 1e6 + 2;
int64 phash[maxn], phashinv[maxn];

void solve(int id){
  string s;
  cin >> s;
  int n = s.size();
  s = "/" + s;
  vector <int64> hs (n + 1);
  phash[0] = 1;
  phashinv[0] = 1;
  for (int i = 1; i <= n; i++){
    phash[i] = phash[i-1] * hash_p % mod;
    phashinv[i] = phashinv[i-1] * hash_inv % mod;
    hs[i] = (s[i] - '0' + 1) * phash[i-1] + hs[i-1];
  }
  auto get_hash = [&] (int l, int r) {
    return ((hs[r] - hs[l-1] + mod) % mod * phashinv[l-1] + mod) % mod; ;
  };
  int rs = 0, last = 1;
  for (int i = 1; i <= n / 2; i++){
    // cout << get_hash(last, i) << " " << get_hash(n - i + 1, n - last + 1) << "\n";
    if (get_hash(last, i) == get_hash(n - i + 1, n - last + 1)) {
      rs++;
      last = i + 1;
    }
  }
  // cout << last << " " << n % 2 << "\n";
  cout << rs * 2 + (last != n / 2 + 1 || n % 2) << "\n";
  return;
}


int main(){
  ios_base::sync_with_stdio(0); cin.tie(0); cout << fixed; cout << setprecision(10);
  qr;
  return 0;
}

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