Problem1.java

/***
 * This problem was recently asked by Google.
 *
 * Given a list of numbers and a number k, return whether any two numbers from the list add up to k.
 *
 * For example, given [10, 15, 3, 7] and k of 17, return true since 10 + 7 is 17.
 *
 * Bonus: Can you do this in one pass?
 */

import java.util.HashSet;
import java.util.Set;

public class Problem1 {

    public static void main(String[] args) {

        System.out.println(contains(107));
    }

    static boolean contains(int k) {
        Set<Integer> set = new HashSet<>();
        int[] list = {10,15,3,7,100,200};
        for (int i : list) {
            if (set.contains(k - i)) return true;
            set.add(i);
        }
        return false;
    }
}