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  1. #include <bits/stdc++.h>
  2. #include <ext/algorithm>
  3. #include <ext/numeric>
  4.  
  5. using namespace std;
  6. using namespace __gnu_cxx;
  7.  
  8. #define endl '\n'
  9.  
  10. vector<int> manacher(const string &s)
  11. {
  12. 	int n = 2 * s.length();
  13. 	vector<int> rad(n);
  14.  
  15. 	for (int i = 0, j = 0, k; i < n; i += k, j = max(j - k, 0))
  16. 	{
  17. 		for( ; i >= j && i + j + 1 < n 
  18. 			&& s[(i - j) / 2] == s[(i + j + 1) / 2]; ++j);
  19.  
  20. 		rad[i] = j;
  21.  
  22. 		for (k = 1; i >= k && rad[i] >= k 
  23. 			&& rad[i - k] != rad[i] - k; ++k)
  24. 			rad[i + k] = min(rad[i - k], rad[i] - k);
  25. 	}
  26.  
  27. 	return rad;
  28. }
  29.  
  30. int main()
  31. {
  32. 	ios_base::sync_with_stdio(0);
  33. 	cin.tie(0);
  34.  
  35. 	int n;
  36. 	string s;
  37. 	cin >> n >> s;
  38.  
  39. 	auto rad = manacher(s);
  40. 	cout << *max_element(rad.begin(), rad.end()) << endl;
  41.  
  42. 	return 0;
  43. }
  44.  
Success #stdin #stdout 0s 3232KB
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https://ideone.com/tM8epU
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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