interview practice

find unique value

import java.util.*;
public class Test {
  
	// You are given an array with n positive integers where all values in the array are repeated except for one. 
	// Return the one that is not repeated.   

	// brute force answer
	public static int notRepeated_bf(int[] integers) {
		int not_repeated;
		int current_num;
		boolean duplicate = false;
		for(int i = 0; i < integers.length; i++) {
			duplicate = false;
			current_num = integers[i];
			System.out.println(current_num);
			for(int j = 0; j < integers.length; j++) {
				System.out.println("Comparing " + integers[j] + " to " + current_num);
				if (integers[j] == current_num && j != i) {
					//its a duplicate
					duplicate = true;
				}
			}
			if (duplicate == false) {
				return current_num;
			}
		}
		return -1;
	}
	
	// "optimal"
	public static int notRepeated(int[] ints) {
		Map<Integer, Integer> m = new HashMap<Integer,Integer>();
		for(int i = 0; i < ints.length; i++) {
			if(m.containsKey(ints[i])) {
				m.put(ints[i], m.get(ints[i]) + 1);
			} else {
				m.put(ints[i], 1);
			}
		}
		
		for (Map.Entry<Integer, Integer> entry : m.entrySet()) {
    		int key = entry.getKey();
    		int occurences = entry.getValue();
			if (occurences == 1) {
				return key;
			}
		}
		return -1;
	}

	public static void main(String[] args) {
		int[] b = new int[5];
		b[0] = 1;
		b[1] = 1;
		b[2] = 3;
		b[3] = 4;
		b[4] = 3;
		int a = notRepeated(b);
		System.out.println(a);
	}
}