Теперь мой начальник хочет, чтобы я внедрил механизм, который позволяет ему искать элемент в массиве, и дает ему индекс / индексы, где это значение встречается.

Твое задание:

Напишите программу или функцию, которая получает массив и значение (String, Integer, Float или Boolean) и возвращает индексы массива, в котором встречается значение (либо 0, либо 1 индексированное, в зависимости от того, что вы предпочитаете). Если значение отсутствует в массиве, вернуть пустой массив.

Входные данные:

Массив A и значение V, которые могут присутствовать или не присутствовать в A.

Выход:

Массив, содержащий индекс (ы), в котором V встречается в A, или, если V не встречается в A, пустой массив.

Тестовые случаи:

Обратите внимание, что тестовые случаи основаны на 0.

12, [12,14,14,2,"Hello World!",3,12,12]         -> [0,6,7]
"Hello World", ["Hi", "Hi World!", 12,2,3,True] -> []
"a", ["A",True,False,"aa","a"]                  -> [4]
12, [12,"12",12]                                -> [0,2]

Подсчет очков:

Это код-гольф , поэтому выигрывает самая низкая оценка в байтах.

Pyth , 2 байта

0 индексированные.

xE

Попробуйте онлайн! или проверьте все тестовые случаи

объяснение

xEQ  - Full Program. Takes Input from standard input. Q means evaluated input and is implicit at the end of the program.

x   - Get all the indexes of x in y
 E  - Evaluated Input #2 - The value
  Q - The list - Evaluated Input #1

MATL , 2 байта

mf

В mПотребляет два аргумента, и проверяют каждый элемент в массиве, равно ли другой аргумент, fвозвращают индексы записей truthy массива.

Попробуйте онлайн!

Python 3 , 45 байт

-3 байта благодаря @EriktheOutgolfer и @Chris_Rands

lambda y,x:[i for i,j in enumerate(x)if j==y]

Тестирование.

Сегодня я узнал enumerate(x) == zip(range(len(x)),x).

Python 3 , 47 байт

lambda n,l:[x for x in range(len(l))if l[x]==n]

Попробуйте онлайн! или проверьте все тестовые случаи

R (+ pryr), 20 байтов

pryr::f(which(a==b))

Который оценивает функцию

function (a, b) 
which(a == b)

Где либо aможет быть значение для поиска и bвектор, либо наоборот. Когда представлено два вектора неравной длины (одно значение считается вектором длины-1 в R), R обернет более короткий, чтобы соответствовать длине более длинного. Тогда равенство проверяется. Это создает логический вектор. whichобеспечивает индексы, где этот вектор является истинным.

Попробуйте онлайн!

JavaScript, 39 байт

e=>a=>[...a.keys()].filter(i=>a[i]===e)

f=
e=>a=>[...a.keys()].filter(i=>a[i]===e)

console.log(f(12)([12,14,14,2,"Hello World!",3,12,12]));
console.log(f("Hello World")(["Hi", "Hi World!", 12,2,3,true]));
console.log(f("a")(["A",true,false,"aa","a"])); 
console.log(f(12)([12,14,14,2,"Hello World!",3,12,'12']));

Вышеприведенный фрагмент может работать не во всех браузерах, поэтому вот ссылка TIO .

JavaScript (ES6), 44 43 байта

^{Вычеркнуто 44 все еще регулярно 44; (}

v=>a=>a.map((x,i)=>x===v&&++i).filter(x=>x)

Сохранено 1 байт благодаря @Arnauld

let f=
v=>a=>a.map((x,i)=>x===v&&++i).filter(x=>x)
;

console.log(f(12)([12,14,14,2,"Hello World!",3,12,12]));         // => [1,7,8]
console.log(f("Hello World")(["Hi", "Hi World!", 12,2,3,true])); // => []
console.log(f("a")(["A",true,false,"aa","a"]));                  // => [5]

05AB1E , 4 байта

QāsÏ

Попробуйте онлайн!

1-индексироваться.

C #, 88 72 байта

using System.Linq;a=>o=>a.Select((i,n)=>o.Equals(i)?n:-1).Where(n=>n>=0)

Сохранено 16 байт благодаря @LiefdeWen.

Попробуйте онлайн!

Jelly, 3 bytes

⁼€T

Try it online!

-1 thanks to Mr. Xcoder. (dyadic chains)

Haskell, 41 39 bytes

v!l=fst<$>(filter((==v).snd)$zip[1..]l)

Try it online!

Saved two bytes thanks to @flawr

Haskell is statically typed, so I had to use a little workaround to run the test cases.

Husk, 5 bytes

`fNm=

Try it online! 1-indexed.

Explanation

       -- implicitly input a value v and a list L
   m=  -- map "equals v" over the list L, resulting in a list of truthy and falsy values
`fN    -- filter the natural numbers N by discarding the numbers at falsy positions 
          and keeping the ones at truthy positions

Ruby, 46 40 39 bytes

->e,a{i=-1;a.map{|x|i+=1;x==e&&i}-[!1]}

Saved 7 bytes!!! thanks to Eric Duminil.

Try it online.

Ruby, 38 bytes

->e,a{a.each_index.select{|x|a[x]==e}}

Try it online!

Google Sheets, 101 bytes

=IfError(Join(",",Filter(Column(Offset(A1,0,0,1,Counta(Split(B1,",")))),Exact(Split(B1,","),A1))),"")

Value V in A1 and array A in B1 with each entry separated by a comma. Null entires are not allowed (row 5 below shows what happens).

Explanation:

Offset(A1,0,0,1,Counta(Split(B1,","))) returns a range that is one row tall and as many columns wide as there are entries in A1.

=IfError(Join(",",Filter(Column(~),Exact(Split(B1,","),A1))),"") filters the column numbers of that range based on whether or not the value in A1 is exactly each of the values in B1 and concatenates them all in a comma-delineated list.

Clojure, 40 bytes

First attempt at code golf.

keep-indexed maps a function over a collection here, passing the current index into the callback and yielding any non-nil return values.

(fn[a b](keep-indexed #(if(= %2 a)%1)b))

Try it online!

APL (Dyalog Unicode), 2 bytes^SBCS

Takes item to look for as left argument (must be scalar to find an item of the lookup array rather than a subarray) and the lookup array (which may have up to 15 dimensions) as right argument. Returns list of indices, each of which may has as many elements as the number of dimensions in the lookup array.

⍸⍷

Try it online!

⍸ ɩndices where

⍷ found

Batch, 86 bytes

@set i=0
:g
@if "%~2"=="" exit/b
@if %1==%2 echo %i%
@set/ai+=1
@shift/2
@goto g

Takes input as command line parameters (value then the array elements as separate parameters). Note: String quoting is considered part of the match e.g. "1" won't equal 1 (would cost 6 bytes).

Python 2, 49 bytes

lambda l,v:filter(lambda i:l[i]==v,range(len(l)))

Try it online!

Not short enough, but I thought it was cool. ¯\_(ツ)_/¯

Perl 5, 28 bytes

sub{grep$_[$_]eq$_[0],1..@_}

Try it online!

The output is 1-indexed.
An anonymous function is quite unusual for Perl, but it happens to be the shortest I could think of. grep ..., 1 .. @_ iterates over the indexes of the input array (actually it goes one cell beyond the last, but it doesn't matter), keeping only the index that satisfy $_[$_]eq$_[0], ie. the ones where the value of the element ($_[$_]) is the same as the value we need to keep ($_[0]).

Slightly longer (31 bytes (30 + -l flag)), but as a full program:

$@=<>;$@eq$_&&print$.-1while<>

Try it online!

Haskell, 37 33 bytes

import Data.List
findIndices.(==)

Thanks @Laikoni for -4 bytes!

Try it online!

Java 8, 146 113 112 111 110 108 bytes

import java.util.*;l->o->{List r=new Stack();for(int i;(i=l.indexOf(o))>-1;l.set(i,null))r.add(i);return r;}

-2 bytes thanks to @TAsk by using Vector instead of ArrayList.
-1 byte by using Stack instead of Vector.
-2 bytes thanks to @Jakob by inputting a ArrayList instead of an array.

0-indexed

Explanation:

Try it here.

import java.util.*;    // Required import for Vector and Vector
l->o->{                // Method with List and Object parameters
  List r=new Stack();  //  Result-list
  for(int i;(i=l.indexOf(o))>=-1;
                       //  Loop as long as we can find the object in the list
    l.set(i,null))     //   After every iteration, remove the found item from the list
      r.add(i);        //    Add the index to the result-list
                       //  End of loop (implicit / single-line body)
  return r;            //  Return the result-List
}                      // End of method

05AB1E, 4 bytes

Qƶ0K

Try it online!

It is 1-indexed, as shown below:

IN A-#------------------------> [2,3,3,3,4]
IN B-#------------------------> 3
-----#------------------------+-----------------
Q    # Vectorized equivalence | [0,1,1,1,0]
 ƶ   # Lift by index          | [0,2,3,4,0]
  0K # Remove zeros           | [2,3,4]

Mathematica, 12 bytes

Position@##&

1-Indexed

input [Array,Value]

[{12, 14, 14, 2, "Hello World!", 3, 12, 12}, 12]

output

{{1}, {7}, {8}}

Haskell, 29 bytes

e#l=[i|(i,h)<-zip[0..]l,h==e]    

Try it online!

Japt, 9 bytes

mȶV©YÄÃf

1-indexed.

Japt input doesn't support booleans, so they have been replaced with 0 and 1 in the test cases.

Try it online! with the -Q flag to format the array output.

0-indexed Solution, 11 bytes

l o f@gX ¶V

Try it online!

Perl 6, 21 bytes

{grep :k,*===$^v,@^z}

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The :k adverb to grep tells it to return the matching keys (indices) of the input sequence that match the predicate * === $^v.

If strings and numbers were considered equivalent, one could use a grep predicate of just $^v instead of * === $^v.

Common Lisp, 66 bytes

(lambda(x s)(loop as i in s as j from 0 when(equal i x)collect j))

Try it online!

TXR Lisp, 26 bytes

(op where(op equal @@1)@2)

In other words, "Where is argument 2 equal to argument 1?"

Run:

1> (op where(op equal @@1) @2)
#<interpreted fun: lambda (#:arg-01-0166 #:arg-02-0167 . #:rest-0165)>
2> [*1 12 #(12 14 14 2 "Hello world!" 3 12 12)]
(0 6 7)
3> [*1 "Hello World" #("Hi" "Hi world!" 12 2 3 t)]
nil

Clojure, 39 38 bytes

#(filter(comp #{%2}%)(range(count %)))

A bit obscure :) The first input argument is a vec of values and the second one is the searched value. % maps indexes to values, and the set #{%2} returns truthy (the input argument %2) or falsy nil for that value. comp composes these together.

C 340 362 166 115 Bytes

Hello all. My first time here. I figured since I enjoy (attempting) to write optimized code I may as well give this a try.

@Rodney - ~39 bytes from the includes

@Zacharý - 7 bytes with implicit typing

0-indexed.

How to Run:

As per @Arnolds suggestion, the program takes arguments in a much more C friendly manner. This let me reduce the size of the file by a little more than half.

The arguments should be passed in the following order value [element1 ...] where braces indicate optional arguments

You may or may not have to add escaped quotes to any strings that are provided in order to satisfy the condition of 12 != "12". On my system the this can be done in the following manner

prog-name.exe 12 3 "Hello" 12 4 "12"
Returns [2,4]     < This is incorrect

prog-name.exe 12 3 "\"Hello\"" 12 4 "\"12\""
Returns [2]       < Correct

golfed

#define P printf(
b=0;main(int c,char**v){P"[");for(--c;c-1;c--)b|=strcmp(v[1],v[c])?0:P b?",%i":"%i",c-2);P"]");}

ungolfed

#define P printf(

//Implicit only works in global(I totally knew this after almost 4 years of C :P)
b = 0;
main(int c,char**v)
{

    P"[");

    //match loop
    //b is used to determine if this is the first iteration. it can be assumed that printf will always return >0
    //subract two from c to get correct index number of match
    for(--c; c-1; c--)
        b |= strcmp(v[1], v[c]) ? 0 : P b ? ",%i" : "%i", c-2);

    P"]");

    return 0;
}