Submission #977810

#	Time	Username	Problem	Language	Result	Execution time	Memory
977810		duckindog	Palindromic Partitions (CEOI17_palindromic)	C++17	100 / 100	39 ms	26440 KiB

palindromic

#include <bits/stdc++.h>

using namespace std;

const int N = 1'000'000 + 10;
int t;

using ull = unsigned long long;
ull h[N], pw[N];
ull get(int l, int r) { return h[r] - h[l - 1] * pw[r - l + 1]; }

int32_t main() { 
  cin.tie(0)->sync_with_stdio(0);

  pw[0] = 1;
  for (int i = 1; i <= 1'000'000; ++i) pw[i] = pw[i - 1] * 19937;

  cin >> t;
  while (t--) { 
    string s; cin >> s;
    for (int i = 1; i <= s.size(); ++i) h[i] = h[i - 1] * 19937 + s[i - 1];
    
    int l = 1, r = s.size();
    int answer = 0;
    
    int len = 0;
    while (l <= r) {
      if (l + len >= r - len) { answer += 1; break; }
      
      if (get(l, l + len) != get(r - len, r)) len += 1;
      else { 
        answer += 2;
        l = l + len + 1; r = r - len - 1;
        len = 0;
      }
    }

    cout << answer << "\n";
  }
}

Compilation message (stderr)

palindromic.cpp: In function 'int32_t main()':
palindromic.cpp:21:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   21 |     for (int i = 1; i <= s.size(); ++i) h[i] = h[i - 1] * 19937 + s[i - 1];
      |                     ~~^~~~~~~~~~~

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