Find number of times a string occurs as a subsequence in given string | A Dynamic Programming based C ++ program to find the number of times the second string occurs in the first string , whether continuous or discontinuous ; Iterative DP function to find the number of times the second string occurs in the first string , whether continuous or discontinuous ; Create a table to store results of sub - problems ; If first string is empty ; If second string is empty ; Fill lookup [ ] [ ] in bottom up manner ; If last characters are same , we have two options - 1. consider last characters of both strings in solution 2. ignore last character of first string ; If last character are different , ignore last character of first string ; Driver code
#include <iostream> NEW_LINE using namespace std ; int count ( string a , string b ) { int m = a . length ( ) ; int n = b . length ( ) ; int lookup [ m + 1 ] [ n + 1 ] = { { 0 } } ; for ( int i = 0 ; i <= n ; ++ i ) lookup [ 0 ] [ i ] = 0 ; for ( int i = 0 ; i <= m ; ++ i ) lookup [ i ] [ 0 ] = 1 ; for ( int i = 1 ; i <= m ; i ++ ) { for ( int j = 1 ; j <= n ; j ++ ) { if ( a [ i - 1 ] == b [ j - 1 ] ) lookup [ i ] [ j ] = lookup [ i - 1 ] [ j - 1 ] + lookup [ i - 1 ] [ j ] ; else lookup [ i ] [ j ] = lookup [ i - 1 ] [ j ] ; } } return lookup [ m ] [ n ] ; } int main ( ) { string a = " GeeksforGeeks " ; string b = " Gks " ; cout << count ( a , b ) ; return 0 ; }