pa04 : Leetcode practice with hashtables and hashmaps

Additional Practice Problems

1. Two sum (easy):https://leetcode.com/problems/two-sum/description/
2. Intersection of Two Arrays (easy) https://leetcode.com/problems/intersection-of-two-arrays/description/
3. Contains Duplicate (easy) https://leetcode.com/problems/contains-duplicate/description/
4. Ransom Note (easy) https://leetcode.com/problems/ransom-note/description/
5. Happy Number (easy) https://leetcode.com/problems/happy-number/description/
6. 4Sum II (medium) https://leetcode.com/problems/4sum-ii/description
7. 3Sum (medium) https://leetcode.com/problems/3sum/description/
8. 4Sum (medium) https://leetcode.com/problems/4sum/description/
9. Longest Consecutive Sequence (medium) https://leetcode.com/problems/longest-consecutive-sequence/description/