Number of subsequences as " ab " in a string repeated K times | Java code to find number of subsequences of " ab " in the string S which is repeated K times . ; Count of ' a ' s ; Count of ' b ' s ; occurrence of " ab " s in string S ; Add following two : 1 ) K * ( Occurrences of " ab " in single string ) 2 ) a is from one string and b is from other . ; Driver code
import java . io . * ; class GFG { static int countOccurrences ( String s , int K ) { int n = s . length ( ) ; int C = 0 , c1 = 0 , c2 = 0 ; for ( int i = 0 ; i < n ; i ++ ) { if ( s . charAt ( i ) == ' a ' ) c1 ++ ; if ( s . charAt ( i ) == ' b ' ) { c2 ++ ; C += c1 ; } } return C * K + ( K * ( K - 1 ) / 2 ) * c1 * c2 ; } public static void main ( String [ ] args ) { String S = " abcb " ; int k = 2 ; System . out . println ( countOccurrences ( S , k ) ) ; } }