Task 1: "Strobogrammatic Number

A strobogrammatic number is a number that looks the same when looked at
upside down.

You are given two positive numbers $A and $B such that 1 <= $A <= $B <= 10^15.

Write a script to print all strobogrammatic numbers between the given
two numbers.

Example

Input: $A = 50, $B = 100
    Output: 69, 88, 96
"

My notes: ok.  Wikipedia suggests 0, 1, 6, 8 and 9 are only digits to consider,
0, 1 and 8 are their own inverses, and 6 and 9 form the only inverse pair
(unless you include 2 and 5 like on an 8-segment lcd display).


Task 2: "0/1 String

A 0/1 string is a string in which every character is either 0 or 1.

Write a script to perform switch and reverse to generate S30 as described below:

switch:

Every 0 becomes 1 and every 1 becomes 0. For example, '101' becomes '010'.

reverse:

The string is reversed. For example, "001" becomes "100".

Please follow the rule as below:

S0 = ""
S1 = "0"
S2 = "001"
S3 = "0010011"

SN = SN-1 + '0' + switch(reverse(SN-1))

My notes: ok.  Defined by a recursive recurrence relation.  switch means 1s-complement.