Find number of times a string occurs as a subsequence in given string | Recursive function to find the number of times the second string occurs in the first string , whether continuous or discontinuous ; If both first and second string is empty , or if second string is empty , return 1 ; If only first string is empty and second string is not empty , return 0 ; If last characters are same Recur for remaining strings by 1. considering last characters of both strings 2. ignoring last character of first string ; If last characters are different , ignore last char of first string and recur for remaining string ; Driver code
function count ( a , b , m , n ) { if ( ( m == 0 && n == 0 ) n == 0 ) return 1 ; if ( m == 0 ) return 0 ; if ( a [ m - 1 ] == b [ n - 1 ] ) return count ( a , b , m - 1 , n - 1 ) + count ( a , b , m - 1 , n ) ; else return count ( a , b , m - 1 , n ) ; } var a = " " ; var b = " " ; document . write ( count ( a , b , a . length , b . length ) ) ;