Manacher's_Algorithm

#include <bits/stdc++.h>
using namespace std;

string text;

void findLongestPalindromicString()
{
	int N = text.length();
	if(N == 0)
		return;

	N = 2*N + 1;
	int L[N];

	L[0] = 0;
	L[1] = 1;

	int C = 1;
	int R = 2;

	int i = 0;
	int iMirror;
	int maxLPSLength = 0;
	int maxLPSCenterPosition = 0;

	int start = -1;
	int end = -1;
	int diff = -1;

	for (i = 2; i < N; i++)
	{
		iMirror = 2*C-i;
		L[i] = 0;
		diff = R - i;

		if(diff > 0)
			L[i] = min(L[iMirror], diff);

		while (((i + L[i]) < N && (i - L[i]) > 0) && ( ((i + L[i] + 1) % 2 == 0) ||(text[(i + L[i] + 1)/2] == text[(i - L[i] - 1)/2] ))) {
			L[i]++;
		}

		if(L[i] > maxLPSLength) {
			maxLPSLength = L[i];
			maxLPSCenterPosition = i;
		}

		if (i + L[i] > R) {
			C = i;
			R = i + L[i];
		}

	}

	start = (maxLPSCenterPosition - maxLPSLength)/2;
	end = start + maxLPSLength - 1;
	cout << "Longest Palindrome substring of " << text << " is ";

	for(i=start; i<=end; i++)
		cout << text[i];
	cout << "\n";
}

int main() {

	cin >> text;
	findLongestPalindromicString();

	return 0;
}