Interview Question for Software Quality Engineer at Salesforce.com:

HashSet <Integer> hs= new HashSet<Integer>();
for (Integer x: inputArray){
    hs.add(x);
}
s.o.p(hs.size());

//If input: 1,2,3,1,4,6,3,7,8,9,0. Then your code will return 9, but it should return 7.
//Improved code
Set<Integer> distinctSet = new HashSet<Integer>();
for(int i = 0; i<array.length; i++){
    if(!(distinctSet.contains(array[i]))){
        distinctSet.add(array[i]);
    }
    else{
        distinctSet.remove(array[i]);
    }
}
System.out.println(distinctSet.size());