Given an integer array, one element occurs even number of times and all others have odd occurrences. Find the element with even occurrences.
The first thing I thought of was using XOR, but then I realized that I am looking for the even number so it won’t actually work. My next idea was to use a hashtable:
1 – Start on the first elements and create a hashtable with the number of times each character is found
2 – Look for the even number in the hashtable