Geeksforgeeks_Array Duplicates.py

# Array Duplicates
# Difficulty: EasyAccuracy: 18.95%Submissions: 876K+Points: 2Average Time: 20m
# Given an array arr[] of size n, containing elements from the range 1 to n, and each element appears at most twice, return an array of all the integers that appears twice.

# Note: You can return the elements in any order but the driver code will print them in sorted order.

# Examples:

# Input: arr[] = [2, 3, 1, 2, 3]
# Output: [2, 3] 
# Explanation: 2 and 3 occur more than once in the given array.
# Input: arr[] = [3, 1, 2] 
# Output: []
# Explanation: There is no repeating element in the array, so the output is empty.
# Constraints:
# 1 ≤ n ≤ 106
# 1 ≤ arr[i] ≤ n


from collections import Counter
class Solution:
    def findDuplicates(self, arr):
        # code here
        cmt1 = Counter(arr)
        res = [num for num, freq in cmt1.items() if freq > 1]
        return res