ProblemSolutions.java

/******************************************************************
 *
 *   Malec Basel Tarabein / 002
 *
 *   This java file contains the problem solutions of isSubSet, findKthLargest,
 *   and sort2Arrays methods. You should utilize the Java Collection Framework for
 *   these methods.
 *
 ********************************************************************/

 import java.util.*;

 class ProblemSolutions {
 
     /**
      * Method: isSubset()
      *
      * Given two arrays of integers, A and B, return whether
      * array B is a subset if array A. Example:
      *      Input: [1,50,55,80,90], [55,90]
      *      Output: true
      *      Input: [1,50,55,80,90], [55,90, 99]
      *      Output: false
      *
      * The solution time complexity must NOT be worse than O(n).
      * For the solution, use a Hash Table.
      *
      * @param list1 - Input array A
      * @param list2 - input array B
      * @return      - returns boolean value B is a subset of A.
      */
 
     public boolean isSubset(int list1[], int list2[]) {
 
         // ADD YOU CODE HERE -- DON'T FORGET TO ADD YOR NAME AT TOP OF FILE

         Set<Integer> set = new HashSet<Integer>();

         // part 1: put list1 in set
         for(int num : list1) {
            set.add(num);
         }

         // part 2: check if set contains all integers
         for(int num : list2) {
            if (!set.contains(num))
                return false;
         }
 
         return true;
     }
 
 
     /**
      * Method: findKthLargest
      *
      * Given an Array A and integer K, return the k-th maximum element in the array.
      * Example:
      *      Input: [1,7,3,10,34,5,8], 4
      *      Output: 7
      *
      * @param array - Array of integers
      * @param k     - the kth maximum element
      * @return      - the value in the array which is the kth maximum value
      */
 
     public int findKthLargest(int[] array, int k) {
 
         // ADD YOUR CODE HERE

         PriorityQueue<Integer> pq = new PriorityQueue<Integer>();

         for(int num : array) {
            pq.add(-1 * num);
         }

         for(int i = 1; i < k; i++) {
            pq.poll();
         }

         Integer result = pq.poll();
 
         return (result == null ? null : -1 * (int)result);
     }
 
 
     /**
      * Method: sort2Arrays
      *
      * Given two arrays A and B with n and m integers respectively, return
      * a single array of all the elements in A and B in sorted order. Example:
      *      Input: [4,1,5], [3,2]
      *      Output: 1 2 3 4 5
      *
      * @param array1    - Input array 1
      * @param array2    - Input array 2
      * @return          - Sorted array with all elements in A and B.
      */
 
     public int[] sort2Arrays(int[] array1, int[] array2) {
 
         // ADD YOU CODE HERE

         int[] result = new int[array1.length + array2.length];
 
         for(int i = 0; i < array1.length; i++) {
            result[i] = array1[i];
         }

         for(int i = 0; i < array2.length; i++) {
            result[i + array1.length] = array2[i];
         }

         Arrays.sort(result);

         return result;
     }
 
 }