karimhamdanali / codility Goto Github PK

When I check the second solution on official codility website
Found some of "Wrong answer"
But unfortunately, they not support us with failed test cases data

If the main has the following code System.out.println(solution(new int[] { 7, 9, 3, 9, 3, 9, 9 })); an incorrect number is returned by solution2.
The below code for solution2 works well and is of same order:

public static int solution2(int[] A) {
	// write your code in Java SE 8
	HashSet<Integer> dups = new HashSet<Integer>();
	ArrayList<Integer> tmp = new ArrayList<>();
	for (int i = 0; i < A.length; i++) {
		if (dups.add(A[i])) {
			tmp.add(A[i]);
		}
		else{
			tmp.remove(new Integer(A[i]));
		}
	}
	return tmp.get(0);
}

If the main has the following code System.out.println(solution(new int[] { 7, 9, 3, 9, 3, 9, 9 })); an incorrect number is returned by solution2.
The below code for solution2 works well and is of same order:

public static int solution2(int[] A) {
	// write your code in Java SE 8
	HashSet<Integer> dups = new HashSet<Integer>();
	ArrayList<Integer> tmp = new ArrayList<>();
	for (int i = 0; i < A.length; i++) {
		if (dups.add(A[i])) {
			tmp.add(A[i]);
		}
		else{
			tmp.remove(new Integer(A[i]));
		}
	}
	return tmp.get(0);
}

Came upon this code through google search

If the input array is arranged so that the odd number occurs before the pairs, the output will be the last number did not exist in the set, which may not necessarily be the odd number.
for example, {7, 9, 3, 9, 3, 9, 9} will return 3