def arrayIsEqual? (numArray, x)
  return true if numArray.sample + numArray.sample == x
  return false if numArray.empty? || numArray.count == 1
end

numArray = [4,2,7,5]
x = 11

def contains_pair_for_sum?(arr, n)
  !!arr.uniq.combination(2).detect { |a, b| a + b == n }
end

array = [4, 5, 9, 7, 8]

contains_pair_for_sum?(array, 11)
# => true (because [4, 7] sums to 11)

contains_pair_for_sum?(array, 17)
# => true (because [9, 8] sums to 17)

contains_pair_for_sum?(array, 100)
# => false (no pair matched)

def has_pair_equal?(num_array, x)
  (0..num_array.length-1).any? do |i|
    num_array[i+1..-1].any? { |n| n + num_array[i] == x }
  end
end

def array_is_equal? (num_array, x)
  equality = 0
  num_array.each do |a|
    equality += 1 if a == x
    return true if equality == 2
  end
  return false
end

x=[4,2,7,5]; x.each_with_index.any? {|y,i| x.each_with_index.any? {|z,j| unless i==j; z+y==11; end } }

def pair_sum_match?(arr, x)
    arr.each_with_index.any? do |y,i|
        arr.each_with_index.any? do |z,j|
            unless i==j
                z+y==x
            end
        end
    end
end

numbers = ( -10..10 ).to_a
numbers.unshift( numbers.first + -1 ) # if you do -20 or 20
numbers.push( numbers.last + 1 )
target    = 5
searched  = { }
matches   = { }
numbers.each do |number|
  if searched[ target - number + 1 ] == true
    matches[ "#{ number }_plus_#{ target - number }" ] = target
  end
  searched[ number + 1 ] = true
end
ap matches