Adding Efficient Solution for Problem - 442 - Find Duplicates Array

Author: Vanditg

Find_Duplicates_Array/EfficientSolution.py

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+##==================================
+## Leetcode
+## Student: Vandit Jyotindra Gajjar
+## Year: 2020
+## Problem: 442
+## Problem Name: Find All Duplicates in an Array  
+##===================================
+#
+#Given an array of integers, 1 ≤ a[i] ≤ n (n = size of array), some elements appear twice and others appear once.
+#
+#Find all the elements that appear twice in this array.
+#
+#Could you do it without extra space and in O(n) runtime?
+#
+#Example:
+#Input:
+#[4,3,2,7,8,2,3,1]
+#
+#Output:
+#[2,3]
+import collections	#Importing collections module 
+class Solution:
+    def findDuplicates(self, nums):
+        return ([item for item, count in collections.Counter(nums).items() if count > 1])	#Returning elements list appearing more than one time.