Longest Non-Overlapping Prefix Suffix

PYTHON:

def LengthlongestPrefixSuffix(s): 

n = len(s) 

lps = [0 for i in range(n)] 

len1 = 0

i = 1

while (i < n): 

if (s[i] == s[len1]): 

len1 += 1

lps[i] = len1 

i += 1

else:

if (len1 != 0): 

len1 = lps[len1 - 1] 

else: 

lps[i] = 0

i += 1

res = lps[n - 1]

if (res > int(n / 2)): 

return int(n / 2) 

else: 

return res 

def longestPrefixSuffix(s): 

len1 = LengthlongestPrefixSuffix(s) 

prefix = "" 

for i in range(len1): 

prefix += s[i] 

return prefix 

s =input().strip()

ans = longestPrefixSuffix(s) 

if (ans == ""): 

print("-1") 

else: 

print(ans)