51nod 1089 最长回文字串V2(Manacher算法)

直接套模板。

#include 
#include 

using namespace std;

string preProvess(string s)
{
	int n = s.size();
	if (n == 0)
		return "^$";
	string ret = "^";
	for (int i = 0; i < n; ++i)
		ret += "#" + s.substr(i, 1);

	ret += "#$";
	return ret;
}

int longgest_palindrome(string s)
{
	string T = preProvess(s);
	int n = T.size();
	int* p = new int[n];
	int C = 0, R = 0;
	for (int i = 1; i < n - 1; ++i)
	{
		int i_mirror = 2 * C - i;
		p[i] = (R > i) ? min(R - i, p[i_mirror]) : 0;
		while (T[i + 1 + p[i]] == T[i - 1 - p[i]])
			p[i]++;
		if (i + p[i] > R)
		{
			C = i;
			R = i + p[i];
		}
	}

	int max_len = 0;
	int centerIndex = 0;
	for (int i = 1; i < n - 1; ++i)
	{
		if (p[i] > max_len)
		{
			max_len = p[i];
			centerIndex = i;
		}	

	}

	delete[] p;
	return max_len;
}


int main()
{
	string tmp;
	cin >> tmp;
	cout << longgest_palindrome(tmp) << endl;
	return 0;
}