[Ruby] Combinations

Combinations

Write a method combinations that takes in an array of unique elements, the method should return a 2D array representing all possible combinations of 2 elements of the array.

def combinations(arr)

end

print combinations(["a", "b", "c"]); # => [ [ "a", "b" ], [ "a", "c" ], [ "b", "c" ] ]
puts

print combinations([0, 1, 2, 3]); # => [ [ 0, 1 ], [ 0, 2 ], [ 0, 3 ], [ 1, 2 ], [ 1, 3 ], [ 2, 3 ] ]
puts

doh solution

def combinations(arr)
  
  new_arr = []
  
  i = 0
  while i < arr.length
  	j = i+1
    while j < arr.length
    	new_arr << [arr[i].to_s, arr[j].to_s]
    	j += 1
    end
    i += 1
  end
	return new_arr
end

print combinations(["a", "b", "c"]); # => [ [ "a", "b" ], [ "a", "c" ], [ "b", "c" ] ]
puts

print combinations([0, 1, 2, 3]); # => [ [ 0, 1 ], [ 0, 2 ], [ 0, 3 ], [ 1, 2 ], [ 1, 3 ], [ 2, 3 ] ]
puts

solution

def combinations(arr)
  pairs = []

  arr.each_with_index do |ele1, idx1|
    arr.each_with_index do |ele2, idx2|
      if idx2 > idx1
        pairs << [ ele1, ele2 ]
      end
    end
  end

  return pairs
end

print combinations(["a", "b", "c"]); # => [ [ "a", "b" ], [ "a", "c" ], [ "b", "c" ] ]
puts

print combinations([0, 1, 2, 3]); # => [ [ 0, 1 ], [ 0, 2 ], [ 0, 3 ], [ 1, 2 ], [ 1, 3 ], [ 2, 3 ] ]
puts