Longest Common Prefix using Divide and Conquer Algorithm | Java Program to find the longest common prefix ; A Utility Function to find the common prefix between strings - str1 and str2 ; A Divide and Conquer based function to find the longest common prefix . This is similar to the merge sort technique ; Same as ( low + high ) / 2 , but avoids overflow for large low and high ; Driver program to test above function
class GFG { static String commonPrefixUtil ( String str1 , String str2 ) { String result = " " ; int n1 = str1 . length ( ) , n2 = str2 . length ( ) ; for ( int i = 0 , j = 0 ; i <= n1 - 1 && j <= n2 - 1 ; i ++ , j ++ ) { if ( str1 . charAt ( i ) != str2 . charAt ( j ) ) { break ; } result += str1 . charAt ( i ) ; } return ( result ) ; } static String commonPrefix ( String arr [ ] , int low , int high ) { if ( low == high ) { return ( arr [ low ] ) ; } if ( high > low ) { int mid = low + ( high - low ) / 2 ; String str1 = commonPrefix ( arr , low , mid ) ; String str2 = commonPrefix ( arr , mid + 1 , high ) ; return ( commonPrefixUtil ( str1 , str2 ) ) ; } return null ; } public static void main ( String [ ] args ) { String arr [ ] = { " geeksforgeeks " , " geeks " , " geek " , " geezer " } ; int n = arr . length ; String ans = commonPrefix ( arr , 0 , n - 1 ) ; if ( ans . length ( ) != 0 ) { System . out . println ( " The ▁ longest ▁ common ▁ prefix ▁ is ▁ " + ans ) ; } else { System . out . println ( " There ▁ is ▁ no ▁ common ▁ prefix " ) ; } } }