Question

(JAVA) Given an array of unique positive integers, write a function findSums that takes the array input and:

1. Creates a hashtable called “hashT” and inserts all the elements of the input array in the hashtable.

2. Finds pairs of elements in the hashtable whose sum is another element (sum) in the hashtable and print the pairs in the console.

3. Returns another hashtable names “sums” of those sum elements.
For example:

Input: [1,5,4,6,7,9]

Output: [6,5,7,9]

Explanation: 6 = 1 + 5 ; 5 = 1 + 4 ; 7 = 1 + 6 ; 9 = 5 + 4

This is what I have so far

import java.util.HashSet;

public class FindSum {

   public static void main(String[] args) {
       // TODO Auto-generated method stub
       int[]arr = {1, 5, 4, 6, 7, 9};
       HashSet<Integer> res = findSums(arr);
       System.out.println(res.toString()); //Should return [6, 5, 7, 9]
   }
   @SuppressWarnings("unlikely-arg-type")
   public static HashSet<Integer> findSums(int[] arr){
       HashSet<Integer> sums = new HashSet<Integer>();
       HashSet<Integer> hashtable = new HashSet<Integer>();
       for(int i = 0; i < arr.length; i++ ) {
           sums.add(arr[i]);
           hashtable.add(arr[i]);
          
           if(hashtable.contains(sums)) {
               sums = sums - arr[i];
           }
       }
      
       return sums;
   }

}

Answer 1

import java.util.HashSet;

public class FindSum {

public static void main(String[] args) {
int ar[]={1,5,4,6,7,9};
HashSet<Integer> res=findSum(ar);
System.out.println(res.toString());
  

}
public static HashSet<Integer> findSum(int element[]){
HashSet<Integer> sums=new HashSet<Integer>();
HashSet<Integer> hashtable =new HashSet<Integer>();
for(int i=0;i<element.length;i++){
hashtable.add(element[i]); //add all element to hashtable
}
for(int i=0;i<element.length;i++){
for(int j=i;j<element.length;j++){ //it will calculate each pair
int sum=element[i]+element[j]; //sum of the that pair
if(hashtable.contains(sum)){ //if that sum present in hashtable add to to set
sums.add(sum);
}
}
}
return sums; //return set
}

}

output

[5, 6, 7, 9]