Problems: BestTime To Buy and Sell
Permutations I
mergeTwoSortedLists

Problem Description:
Best Time to Buy and Sell
Say you have an array for which the ith element is the price of a given stock on day i.

If you were only permitted to complete at most one transaction (ie, buy one and sell one share of the stock), design an algorithm to find the maximum profit.

Permutations I:
Given a collection of numbers, return all possible permutations.

For example,
[1,2,3] have the following permutations:
[1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,2,1].

Merge Two Sorted Linked Lists:
Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.