return the number of common subsequence in two strings
int CommomSubsequencesCount ( string s , string t ) { int n1 = s . length ( ) ; int n2 = t . length ( ) ; int dp [ n1 + 1 ] [ n2 + 1 ] ; for ( int i = 0 ; i <= n1 ; i ++ ) { for ( int j = 0 ; j <= n2 ; j ++ ) { dp [ i ] [ j ] = 0 ; } }