LeetCode Problem Solution : TwoSum III

Java solution for LeetCode Two Sum design problem:

package com.kpatil.leetcode;

import java.util.HashMap;
import java.util.Map;

/**
 * Design and implement TwoSum class, to support following methods: add and find
 * 
 * add(input) - add the number input two the internal data structure find(value)
 * - find if there exists any pair of numbers which sum is equal to the value
 *
 * e.g. add(1), add(3), add(5); find(4) -> true, find(7) -> false
 * 
 */

// Store each input into a hash table with the input as a key
// and it's count (no of times it is added) as value.
// To find if a pair sum exists, just iterate through the hash table in O(n) runtime.
// Make sure to handle duplicates

public class TwoSum {
 // O(n) space
 private Map lookupTable = new HashMap<>();

 // O(1) runtime
 public void add(int input) {
  int count = lookupTable.containsKey(input) ? lookupTable.get(input) : 0;
  lookupTable.put(input, count + 1);
 }

 // O(n) runtime
 public boolean find(int val) {

  for (Map.Entry entry : lookupTable.entrySet()) {
   int num = entry.getKey();
   int diff = val - num;
   if (diff == num) {
    // for duplicates, make sure there are at least two individual numbers
    if (entry.getValue() >= 2)
     return true;
   } else if (lookupTable.containsKey(diff)) {
    return true;
   }
  }

  return false;
 }

 public void print() {
  System.out.println("---------------------------------------------");
  for (Map.Entry entry : lookupTable.entrySet()) {
   System.out.println(entry.getKey() + " : " + entry.getValue());
  }
  System.out.println("---------------------------------------------");
 }

}

JUnit Test:

package com.kpatil.leetcode.test;

import static org.junit.Assert.*;

import org.junit.Test;

import com.kpatil.leetcode.TwoSum;

public class TwoSumTest {

 @Test
 public void testTwoSum() {
  TwoSum twoSum3 = new TwoSum();
  
  twoSum3.add(1);
  twoSum3.print();
  
  twoSum3.add(3);
  twoSum3.print();
  
  twoSum3.add(5);
  twoSum3.print();
  
  twoSum3.add(5);
  twoSum3.print();
  
  twoSum3.add(1);
  twoSum3.print();
  
  twoSum3.add(10);
  twoSum3.print();
  
  boolean found = twoSum3.find(4);
  assertEquals(found,true);
  
  boolean notFound = twoSum3.find(7);
  assertEquals(notFound,false);
  
  boolean found2 = twoSum3.find(10);
  assertEquals(found2,true);
  
  boolean found3 = twoSum3.find(11);
  assertEquals(found3,true);
  
  boolean nfound2 = twoSum3.find(12);
  assertEquals(nfound2,false);
 }
 

}