Description:

Given an array of one's and zero's convert the equivalent binary value to an integer.

Eg: [0, 0, 0, 1] is treated as 0001 which is the binary representation of 1

Examples:

Testing: [0, 0, 0, 1] ==> 1
Testing: [0, 0, 1, 0] ==> 2
Testing: [0, 1, 0, 1] ==> 5
Testing: [1, 0, 0, 1] ==> 9
Testing: [0, 0, 1, 0] ==> 2
Testing: [0, 1, 1, 0] ==> 6
Testing: [1, 1, 1, 1] ==> 15
Testing: [1, 0, 1, 1] ==> 11

Solution :

Ruby

def binary_array_to_number(arr)
  arr.join("").to_i(2)
end 

JavaScript

const binaryArrayToNumber = arr => {
  // your code
  return (arr[0] * 8) +
         (arr[1] * 4) +
         (arr[2] * 2) +
         (arr[3] * 1);
};

Test Cases: Ruby

Test.describe("Example tests") do
Test.assert_equals(binary_array_to_number([0,0,0,1]), 1)
Test.assert_equals(binary_array_to_number([0,0,1,0]), 2)
Test.assert_equals(binary_array_to_number([1,1,1,1]), 15)
Test.assert_equals(binary_array_to_number([0,1,1,0]), 6)
end 
Test.describe("Random tests") do

def randint(a,b) rand(b-a+1)+a end

50.times do
  n = randint(0,1000)
  array = n.to_s(2).split("").map(&:to_i)
  Test.it("Tests #{array} ==> #{n}") do
  Test.assert_equals(binary_array_to_number(array), n, "It should work for random inputs too")
  end
end
end