Count pairs of characters in a string whose ASCII value difference is K | Java implementation of the approach ; Function to return the count of required pairs of characters ; Length of the string ; To store the frequency of each character ; Update the frequency of each character ; To store the required count of pairs ; If ascii value difference is zero ; If there exists similar characters more than once ; If there exits characters with ASCII value difference as k ; Return the required count ; Driver code
import java . util . Arrays ; class GFG { static int MAX = 26 ; static int countPairs ( char [ ] str , int k ) { int n = str . length ; int [ ] freq = new int [ MAX ] ; for ( int i = 0 ; i < n ; i ++ ) { freq [ str [ i ] - ' a ' ] ++ ; } int cnt = 0 ; if ( k == 0 ) { for ( int i = 0 ; i < MAX ; i ++ ) { if ( freq [ i ] > 1 ) { cnt += ( ( freq [ i ] * ( freq [ i ] - 1 ) ) / 2 ) ; } } } else { for ( int i = 0 ; i < MAX ; i ++ ) { if ( freq [ i ] > 0 && i + k < MAX && freq [ i + k ] > 0 ) { cnt += ( freq [ i ] * freq [ i + k ] ) ; } } ; } return cnt ; } public static void main ( String [ ] args ) { String str = " abcdab " ; int k = 0 ; System . out . println ( countPairs ( str . toCharArray ( ) , k ) ) ; } }