Coding Test - Return a number of distinct values that occur two or more times in an array

count-duplicates.rb

# Count occurrences
# FIND DESCRIPTION BELOW THE CODE

def  countDuplicates array
  puts array.select{|x| array.count(x) > 1}
            .each_with_object(Hash.new(0)) {|num,counts| counts[num] += 1}
            .each_value.to_a.uniq
end
# Usage 
# countDuplicates([1,3,1,4,5,6,3,2,4,4,6,7,6,7,8,8,9,7,7]);
# countDuplicates(%w(how much wood would a wood chuck chuck chuck));

# DESCRIPTION
# Write a program to find the total number of duplicate elements in any array. 
# We want the number of distinct values that occur two or more times, not the number of occurrences.
# Complete the function "countDuplicates" which contains an integer array "numbers" as its argument. 
# Return an integer which denotes the required result.
 
# Constraints:  
# 1 ≤ size of array ≤ 1000  
# 1 ≤ numbers[i] ≤ 1000

# Input Format:
# * Function "countDuplicates" contains an integer array "numbers" as its argument.
 
# Output Format:
# * Return an integer which denotes the required result.
 
# Sample Input #00:
# 1  
# 3  
# 1  
# 4  
# 5  
# 6  
# 3  
# 2  
 
# Sample Output #00:
# 2
 
# Explanation #00:
# * The input gives you:  > array[8] = {1,3,1,4,5,6,3,2}.  
# * The number of duplicate elements in the array is 2, because 1 and 3 both occur more than once.