Path Sum II

Given a binary tree and a sum, find all root-to-leaf paths where each path’s sum equals the given sum.

For example:
Given the below binary tree and sum = 22,

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

return
[
[5,4,11,2],
[5,8,4,5]
]