Remove digits, retaining greater number
MATL, 10 bytes
-jowXncUX>
This uses version (9.2.1) of the language/compiler, which is earlier than this challenge.
It takes three inputs from stdin in this order: string length, number of removed characters, string.
Example
>> matl
> -jowXncUX>
>
> 7
> 4
> 1789823
983
EDIT: Try it online! (the code in the link has XN
instead of Xn
to conform to changes in the language after this challenge; also, o
is not needed anymore)
Explanation
(This still costs 2 bytes more than it should due to Octave's and Matlab's nchoosek
function behaving differently. Fixed in the next release of the compiler.)
- % implicitly input two numbers, and subtract them
jo % input string, and convert to ASCII codes
wXn % swap inputs. Generate all combinations, each in a row
c % convert to char array
U % convert each row to a number
X> % get maximum. Implicitly display
Answer to original challenge (stricter input requirements): 16 bytes
jYbZ)b-wowXncUX>
Uses current version (9.2.1) of the language/compiler.
Example
>> matl jYbZ)b-wowXncUX>
> 4 1789823 7
983
Explanation
(This should have been 4 bytes less, but I need that wow...c
because Octave's nchoosek
function, unlike Matlab's, doesn't work with character input. Will be fixed for next release of the compiler.)
j % input string
YbZ) % split at spaces into strings
b- % subtract first and third (1-digit) strings
wow % convert middle string into ASCII codes
Xn % get all combinations, each in a row
c % convert to char array
U % convert each row to a number
X> % get maximum. Implicitly display
Pyth - 11 9 8 bytes
eS.cz-QE
Test Suite.
A-Ray, 9 7 bytes
My new language! According to meta, this is allowed, but if this is not accepted, then I will remove it.
pM:i-II
Explanation:
:i-II Gets all permutations possible for the given number converted to an array,
with the length of y-x, which is the -II part
M Gets the maximum of the result above
p Prints the resulting array above, with no separators
Example input (number, x, y):
1736413 7 4
Output:
764
You can test this with the .jar file given in the github link.