# Problem C: Pattern Generator

**Input file:** `pat.in`

**Output file:** `pat.out`

Write a program that repeatedly reads two numbers `n` and
`k` and prints all bit patterns of length `n` with
`k` ones in descending order (when the bit patterns are
considered as binary numbers). You may assume that 30 >=
`n` > 0, 8 > `k` >= 0, and `n`
>= `k`. The first number in the input gives the number of
pairs `n` and `k`. The numbers `n` and
`k` are separated by a single space. Leading zeroes in a bit
pattern should be included. See the example below.

## Sample input

3
2 1
2 0
4 2

## Sample output

The bit patterns are
10
01
The bit patterns are
00
The bit patterns are
1100
1010
1001
0110
0101
0011