Find the missing element from the given 2 arrays, second array is duplicate?

Question

Say you are given two arrays where second array is duplicate with one missing element. What should be the best possible way to find that missing element -
array1: [1,2,3,4,5,6,7]
array2: [1,3,4,5,6,7]

Missing Element: 2

Answer 1

Here is a quick tip to solve this programming question: put the elements of the second array in the Hashtable and for every element of the first array, check whether it’s present in the hash or not, O/P all those elements from the first array that are not present in the hash table