Two Sum

Given an array of integers, find two numbers such that they add up to a
specific target number.

The function twoSum should return indices of the two numbers such that
they add up to the target, where index1 must be less than index2. Please
note that your returned answers (both index1 and index2) are not
zero-based.

You may assume that each input would have exactly one solution.

Input: numbers={2, 7, 11, 15}, target=9
Output: index1=1, index2=2
Path Sum(Iterator)

Given a binary tree and a sum, determine if the tree has a root-to-leaf
path such that adding up all the values along the path equals the given
sum.
For example:
Given the below binary tree and sum = 22,

5
/ \
4   8
/   / \
11  13  4
/  \      \
7    2      1

return true, as there exist a root-to-leaf path 5->4->11->2 which sum is
22.