Submission #205626

#	Time	Username	Problem	Language	Result	Execution time	Memory
205626		mihai50000	Palindromes (APIO14_palindrome)	C++17	100 / 100	75 ms	40976 KiB

palindrome

#include <bits/stdc++.h>

using namespace std;

#define int long long

struct PalTree
{
	struct Node
	{
		map <char, int> urm;
		int len;
		int cnt;
		int fail;
	};
	
	int n = 2;
	int ans = 0;
	
	vector <Node> vec;
	
	PalTree(string s) : vec(s.size() + 2)
	{
		vec[0].fail = vec[0].len = -1;
		vec[1].fail = vec[1].len = 0;
		
		int last = 0;
		
		for(int i = 0; i < s.size(); ++i)
		{
			char ch = s[i];
			int pos = last;
			
			while(s[i - vec[pos].len - 1] != ch)
			{
				pos = vec[pos].fail;
			}
			if(vec[pos].urm.count(ch))
			{
				pos = vec[pos].urm[ch];
				vec[pos].cnt++;
				last = pos;
				continue;
			}
			
			vec[n].cnt = 1;
			vec[n].len = vec[pos].len + 2;
			vec[pos].urm[ch] = n;
			
			int fail = vec[pos].fail;
			
			while(fail != -1)
			{
				if(s[i - 1 - vec[fail].len] == ch && vec[fail].urm.count(ch))
				{
					fail = vec[fail].urm[ch];
					break;
				}
				
				fail = vec[fail].fail;
			}
			
			if(fail < 1)
				fail = 1;
			
			vec[n].fail = fail;
			last = n;
			n++;
		}
		
		for(int i = n - 1; i > 0; --i)
		{
			vec[vec[i].fail].cnt += vec[i].cnt;
			ans = max(ans, vec[i].cnt * vec[i].len);
		}
	}
};

main()
{
	string s;
	cin >> s;
	
	PalTree arb(s);
	cout << arb.ans << '\n';
}

Compilation message (stderr)

palindrome.cpp: In constructor 'PalTree::PalTree(std::__cxx11::string)':
palindrome.cpp:29:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i = 0; i < s.size(); ++i)
                  ~~^~~~~~~~~~
palindrome.cpp: At global scope:
palindrome.cpp:79:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main()
      ^

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