Problem1 (https://leetcode.com/problems/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.
Note: A leaf is a node with no children.
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]
]
Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).
For example, this binary tree [1,2,2,3,4,4,3] is symmetric:
1
/ \
2 2
/ \ / \
3 4 4 3 But the following [1,2,2,null,3,null,3] is not:
1
/ \
2 2
\ \
3 3 Note: Bonus points if you could solve it both recursively and iteratively.