Дано не порожній список / масив, що містить лише такі негативні цілі числа, як ця:

[0, 0, 0, 8, 1, 4, 3, 5, 6, 4, 1, 2, 0, 0, 0, 0]

Виведіть список із вилученими кінцевими та провідними нулями.

Вихід для цього буде:

[8, 1, 4, 3, 5, 6, 4, 1, 2]

Деякі інші тестові випадки:

[0, 4, 1, 2, 0, 1, 2, 4, 0] > [4, 1, 2, 0, 1, 2, 4]
[0, 0, 0, 0, 0, 0] > nothing
[3, 4, 5, 0, 0] > [3, 4, 5]
[6] > [6]

Найкоротший код виграє

Желе , 2 байти

Код:

t0

Пояснення:

t   # Trim off...
 0  #  zero at both sides

Спробуйте в Інтернеті!

JavaScript (ES6) 43

a=>(f=a=>a.reverse().filter(x=>a|=x))(f(a))

Менше гольфу

a=>{
  f=a=>a.reverse().filter(x=>a|=x) // reverse and remove leading 0
  // leverage js cast rules: operator | cast operands to integer
  // an array casted to integer is 0 unless the array is made of
  // a single integer value (that is ok for me in this case)
  return f(f(a)) // apply 2 times
}

Тест

F=a=>(f=a=>a.reverse().filter(x=>a|=x))(f(a))

function test(){
  var l=(I.value.match(/\d+/g)||[]).map(x=>+x)
  O.textContent=F(l)
}

test()

#I { width:90%}

<input id=I oninput='test()' value='0 0 1 3 7 11 0 8 23 0 0 0'>
<pre id=O></pre>

CJam, 13 байт

l~{_{}#>W%}2*

З введеним масивом.

Більш дрібна версія:

l~             Puts input on the stack and parse as array
  {       }    Code block
   _           Duplicate the first thing on the stack
    {}#        Finds the index of the first non-0 value in the array, puts it on the stack
       >       Slices the array from that index
        W%     Reverses the array
           2*  Does the code block twice in total

Pyth, 4 байти

.sQ0

Демонстрація:

llama@llama:~$ pyth -c .sQ0
[0, 0, 0, 1, 2, 0, 3, 4, 0, 0, 5, 0, 0, 0, 0]
[1, 2, 0, 3, 4, 0, 0, 5]

З Пітаrev-doc.txt :

.s <seq> <any>
    Strip from A maximal prefix and suffix of A consisting of copies of B.

05AB1E , 4 байти

Код:

0Û0Ü

Спробуйте в Інтернеті!

Пояснення:

0Û    # Trim off leading zeroes
  0Ü  # Trim off trailing zeroes

Використовує кодування CP-1252.

Сітківка, 12 байт

^0 ?

)` 0$

Подача підводного каналу є значною.

Завдяки @Martin Büttner та @FryAmTheEggman за збереження кількох байт.

Спробуйте в Інтернеті

R, 43 байти

function(x)x[cummax(x)&rev(cummax(rev(x)))]

або як читати / записувати STDIN / STDOUT

x=scan();cat(x[cummax(x)&rev(cummax(rev(x)))])

Це знаходить сукупний максимум від початку та кінця (зворотного) рядка. &Оператор перетворює ці два вектори в логічній одиниці одного і того ж розміру , як x, (нулі завжди будуть перетворені в FALSEі все інше , щоб TRUE), таким чином , це робить можливим підмножина з в xвідповідності з умовами зустрічалися.

Хаскелл , 29 байт

t=f.f;f=reverse.dropWhile(<1)

Mathematica 34 27 байт

#//.{0,a___}|{a___,0}:>{a}&

This repeatedly applies replacement rules until such action fails to provide a new output. 7 bytes saved thanks to Alephalpha.

The first rule deletes a zero at the beginning; the second rule deletes a zero at the end of the array.

05AB1E, 4 bytes

0Û0Ü

Basically trimming leading then trailing zeroes of the input, given as an array.

Try it online !

Perl, 19 + 1 = 20 bytes

s/^(0 ?)+|( 0)+$//g

Requires -p flag:

$ perl -pE's/^(0 )+|( 0)+$//g' <<< '0 0 0 1 2 3 4 5 6 0 0 0'
1 2 3 4 5 6

Jelly, 10 bytes

Uo\U,o\PTị

This doesn't use the builtin.

Uo\U            Backward running logical OR
    ,           paired with
     o\         Forward running logical OR
       P        Product
        T       All indices of truthy elements
         ị      Index the input at those values.

Try it here.

Perl, 38 bytes

$\.=$_}{$\=~s/^(0\n)*|(0\n)*\n$//gs

Run with perl -p, (3 bytes added for -p).

Accepts numbers on STDIN, one per line; emits numbers on STDOUT, one per line, as a well-behaved unix utility should.

Only treats numbers represented exactly by '0' as zeroes; it would be possible to support other representations with a few more bytes in the regex.

Longer version, still to be run with -p:

    # append entire line to output record separator
    $\.=$_
}{
    # replace leading and trailng zeroes in output record separator
    $\ =~ s/^(0\n)*|(0\n)*\n$//gs
    # output record separator will be implicitly printed

Expanded version, showing interactions with -p flag:

# implicit while loop added by -p
while (<>) {
    # append line to output record separator
    $\.=$_
}{ # escape the implicit while loop
    # replace leading and traling 
    $\=~s/^(0\n)*|(0\n)*\n$//gs
    # print by default prints $_ followed by
    # the output record separator $\ which contains our answer
    ;print # implicit print added by -p
} # implicit closing brace added by -p

Elixir, 77 bytes

import Enum
z=fn x->x==0 end
reverse(drop_while(reverse(drop_while(l,z)),z))

l is the array.

Edit:wah! copy/pasta fail. of course one has to import Enum, which raises the byte count by 12 (or use Enum.function_name, which will make it even longer).

Vitsy, 13 bytes

Vitsy is slowly getting better... (I'm coming for you Jelly. ಠ_ಠ)

1mr1m
D)[X1m]

This exits with the array on the stack. For readability, the TryItOnline! link that I have provided below the explanation will output a formatted list.

Explanation:

1mr1m
1m      Do the second line of code.
  r     Reverse the stack.
   1m   I'ma let you figure this one out. ;)

D)[X1m]
D       Duplicate the top item of the stack.
 )[   ] If the top item of the stack is zero, do the stuff in brackets.
   X    Remove the top item of the stack.
    1m  Execute the second line of code.

Note that this will throw a StackOverflowException for unreasonably large inputs.

TryItOnline!

R, 39 bytes

function(x)x[min(i<-which(x>0)):max(i)]

Four bytes shorter than David Arenburg's R answer. This implementation finds the first and last index in the array which is greater than zero, and returns everything in the array between those two indices.

MATL, 9 bytes

2:"PtYsg)

Try it online!

Explanation

2:"     % For loop (do the following twice)
  P     %   Flip array. Implicitly asks for input the first time
  t     %   Duplicate
  Ys    %   Cumulative sum
  g     %   Convert to logical index
  )     %   Apply index
        % Implicitly end for
        % Implicitly display stack contents

Dyalog APL, 15 bytes

{⌽⍵↓⍨+/0=+\⍵}⍣2

               ⍣2     Apply this function twice:
{             }       Monadic function:
           +\⍵        Calculate the running sum.
       +/0=           Compare to zero and sum. Number of leading zeroes.
   ⍵↓⍨               Drop the first that many elements from the array.
 ⌽                   Reverse the result.

Try it here.

Ruby, 49 44 bytes

->a{eval ?a+'.drop_while{|i|i<1}.reverse'*2}

Thanks to manatwork for chopping off 5 bytes with a completely different method!

This just drops the first element of the array while it's 0, reverses the array, repeats, and finally reverses the array to return it to the proper order.

Vim 16 Keystrokes

i<input><esc>?[1-9]<enter>lD0d/<up><enter>

The input is to be typed by the user between i and esc, and does not count as a keystroke. This assumes that there will be at least one leading and one trailing zero. If that is not a valid assumption, we can use this slightly longer version: (18 Keystrokes)

i <input> <esc>?[1-9]<enter>lD0d/<up><enter>

ES6, 51 bytes

f=a=>a.map(x=>x?t=++i:f<i++||++f,f=i=0)&&a.slice(f,t)

t is set to the index after the last non-zero value, while f is incremented as long as only zeros have been seen so far.

Perl 6, 23 bytes

{.[.grep(?*):k.minmax]}
{.[minmax .grep(?*):k]}

Usage:

# replace the built-in trim subroutine
# with this one in the current lexical scope
my &trim = {.[.grep(?*):k.minmax]}

say trim [0, 0, 0, 8, 1, 4, 3, 5, 6, 4, 1, 2, 0, 0, 0, 0];
# (8 1 4 3 5 6 4 1 2)
say trim [0, 4, 1, 2, 0, 1, 2, 4, 0];
# (4 1 2 0 1 2 4)
say trim [0, 0, 0, 0, 0, 0];
# ()
say trim [3, 4, 5, 0, 0];
# (3 4 5)
say trim [6];
# (6)

Retina, 11 bytes

+`^0 ?| 0$
<empty>

Quite simple. Recursively replaces zeroes at beginning and end of line.

Try it online!

JavaScript (ES6), 47 bytes

a=>a.join(a="").replace(/(^0+|0+$)/g,a).split(a)

Where a is the array.

Python, 84 characters

def t(A):
 if set(A)<={0}:return[]
 for i in(0,-1):
  while A[i]==0:del A[i]
 return A

JavaScript (ES6), 34 bytes

a=>a.replace(/^(0 ?)*|( 0)*$/g,'')

Input and output are in the form of a space-delimited list, such as "0 4 1 2 0 1 2 4 0".

Javascript (ES6) 40 bytes

a=>/^(0,)*(.*?)(,0)*$/.exec(a.join())[2]

PHP, 56 54 52 bytes

Uses Windows-1252 encoding

String based solution

<?=preg_replace(~ÜÒ×ßÏÖÔƒ×ßÏÖÔÛÜ,"",join($argv,~ß));

Run like this:

echo '<?=preg_replace(~ÜÒ×ßÏÖÔƒ×ßÏÖÔÛÜ,"",join($argv,~ß));' | php -- 0 0 123 234 0 500 0 0 2>/dev/null;echo

If your terminal is set to UTF-8, this is the same:

echo '<?=preg_replace("#-( 0)+|( 0)+$#","",join($argv," "));' | php -- 0 0 123 234 0 500 0 0 2>/dev/null;echo

Tweaks

• Saved 2 bytes by negating strings and dropping string delimiters
• Saved 2 bytes by using short print tag

Python 2, 69 67 bytes

def f(a):
 for i in(0,-1):
  while a and a[i]==0:a.pop(i)
 return a

PowerShell, 49 bytes

($args[0]-join',').trim(',0').trim('0,')-split','

Takes input $args[0] and -joins them together with commas to form a string. We then use the .Trim() function called twice to remove first the trailing and then the leading zeros and commas. We then -split the string on commas back into an array.

Alternate version, without using conversion
PowerShell, 81 bytes

function f{param($a)$a=$a|%{if($_-or$b){$b=1;$_}};$a[$a.Count..0]}
f(f($args[0]))

Since PowerShell doesn't have a function to trim arrays, we define a new function f that will do half of this for us. The function takes $a as input, then loops through each item with a foreach loop |%{...}. Each iteration, we check a conditional for $_ -or $b. Since non-zero integers are truthy, but $null is falsey (and $b, being not previously defined, starts as $null), this will only evaluate to $true once we hit our first non-zero element in the array. We then set $b=1 and add the current value $_ onto the pipeline. That will then continue through to the end of the input array, with zeros in the middle and the end getting added onto the output, since we've set $b truthy.

We encapsulate and store the results of the loop all back into $a. Then, we index $a in reverse order (i.e., reversing the array), which is left on the pipeline and thus is the function's return value.

We call the function twice on the $args[0] input to the program in order to "trim" from the front, then the front again (which is the back, since we reversed). The order is preserved since we're reversing twice.

This version plays a little loose with the rules for an input array of all zeros, but since ignoring STDERR is accepted practice, the program will spit out two (verbose) Cannot index into a null array errors to _{(PowerShell's equivalent of)} STDERR and then output nothing.