(JAVA) Problem description: You will need to write a function int uniqueNumber(int[] array). The input of this function is an int array. This array contains only positive integers. Given that every element in this array appeared twice, except for one unique element which appeared only once. Your job is to find and return this unique number. If every number in this array appeared twice, return -1. If you can solve this problem using only 1 loop, youll get 5 extra points. Sample input/output: Input [3, 3, 2, 4, 4] Output 2 Input [1, 2, 3, 1, 4, 2, 3] Output 4 Input [1] Output 1 Explanation: The only element in this array is unique. Input [1, 1, 2, 2, 3, 3] Output -1 Explanation Every number in this array appeared twice. Hence, the output is -1.