FindSumHashSet.java

package dsa.arrays;

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

public class FindSumHashSet {
 public static void main(String a[]){
  FindSumHashSet sumFinder = new FindSumHashSet();
  sumFinder.begin();
 }
 
 public void begin(){
  int[] sampleArray = getRandomArray(20);
  int randomSum = sampleArray[15] + sampleArray[10];
  System.out.print("ARRAY : ");
  for(int i:sampleArray){
   System.out.print(i+" ");
  }
  System.out.println();
  findPair(sampleArray,randomSum);
 }

 public void findPair(int[] sampleArray, int randomSum) {
  Set<Integer> sampleArraySet = new HashSet<Integer>();
  for(int i=0;i<sampleArray.length;i++){
   sampleArraySet.add(sampleArray[i]);
   int valueToFind = randomSum - sampleArray[i];
   if(sampleArraySet.contains(valueToFind)){
    System.out.println("SUM : "+randomSum);
    System.out.println("PAIR : "+valueToFind+","+sampleArray[i]);
    break;
   }
  }
 }

 private int[] getRandomArray(int size) {
  int[] randomArray = new int[size];
  for(int i=0;i<size;i++){
   randomArray[i] = (int)(Math.random()*10);
  }
  return randomArray;
 }
}
//SAMPLE OUTPUTS

//ARRAY : 7 3 6 4 3 4 7 7 5 1 4 6 2 4 1 7 5 8 9 7 
//SUM : 11
//PAIR : 7,4

//ARRAY : 0 2 9 6 0 7 6 5 1 7 9 0 7 1 2 4 4 3 9 0 
//SUM : 13
//PAIR : 6,7