CHEFSHIP Using Prefix Function

help
,
1

Can someone please explain the approach to this problem using prefix function? Why editorial solution contains two lps array?
Question: CHEFSHIP Problem - CodeChef
Soluttion:

#include <bits/stdc++.h>
 
using namespace std;
 
// char input[] = "input/input00.txt";
// char output[] = "output.txt";
 
const int N = 200010;
 
int a[N],lps1[2][N],lps2[2][N];
string s;
 
void computeLPSArray1(int key) 
{
	int len = 0;
	lps1[key][0] = 0;
	int i = 1; 
 
	while(i < s.size()) 
	{ 
	    if(s[i] == s[len])
	    {
	        len++;
			lps1[key][i] = len;
	        i++;
	    }
	    else
	    {
	        if(len != 0)
	            len = lps1[key][len - 1];
	        else
	        { 
	            lps1[key][i] = 0;
	            i++; 
	        } 
	    } 
	} 
} 
 
void computeLPSArray2(int key) 
{
	int len = 0;
	lps2[key][0] = 0;
	int i = 1; 
 
	while(i < s.size()) 
	{
	    if(s[i] == s[len])
	    {
	        len++;
 
	        if(2*len > i+1)
	        	len = lps1[key][len - 1];
	        
			lps2[key][i] = len;
	        i++;
	    }
	    else
	    {
	        if(len != 0)
	            len = lps1[key][len - 1];
	        else
	        { 
	            lps2[key][i] = 0; 
	            i++; 
	        } 
	    } 
	} 
} 
 
int main()
{
	// freopen(input, "r", stdin);
	// freopen(output, "w", stdout);
 
	int t;
	cin >> t;
 
	while(t--)
	{
		cin >> s;
 
		int n = s.size();
 
		for(int i=0;i<n;i++)
			lps1[0][i] = lps1[1][i] = lps2[0][i] = lps2[1][i] = 0;
 
		computeLPSArray1(0);
		computeLPSArray2(0);
		reverse(s.begin(),s.end());
		computeLPSArray1(1);
		computeLPSArray2(1);
 
		int ans = 0;
 
		for(int i=1;i<n-2;i+=2)
		{
			if((2*lps2[0][i] == (i+1)) && (2*lps2[1][n-i-2] == (n-i-1)))
				ans++;
		}
 
		cout << ans << endl;
	}
 
	return 0;
}