I just implemented a XOR linked list: [code language="c"] #include <stdio.h> #include <malloc.h> #include <memory> struct node { int val = 0; struct node* next = NULL; ...

# 145. Binary Tree Postorder Traversal

Given a binary tree, return the postorder traversal of its nodes' values. For example: Given binary tree `{1,#,2,3}`,
```   1
\
2
/
3
```
return

# 94. Binary Tree Inorder Traversal

Given a binary tree, return the inorder traversal of its nodes' values. For example: Given binary tree `[1,null,2,3]`,
```   1
\
2
/
3
```
return

# 132. Palindrome Partitioning II

Given a string s, partition s such that every substring of the partition is a palindrome. Return the minimum cuts needed for a palindrome partitioning of s. For example, giv...

# 155. Min Stack

Design a stack that supports push, pop, top, and retrieving the minimum element in constant time.
• push(x) -- Push element x onto stack.
• pop() -- Removes the element on top of ...

# 124. Binary Tree Maximum Path Sum

Given a binary tree, find the maximum path sum. For this problem, a path is defined as any sequence of nodes from some starting node to any node in the tree along the parent-child connections. The ...

# Symmetric Tree

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
...
```

# 347. Top K Frequent Elements

Given a non-empty array of integers, return the k most frequent elements. For example, Given `[1,1,1,2,2,3]` and k = 2, return `[1,2]`. Note:
...

# 160. Intersection of Two Linked Lists

Write a program to find the node at which the intersection of two singly linked lists begins.   For example, the following two linked lists:
```A:          a1 → a2
...
```

# Everyone I’m back!

For some stupid reasons, my website had crashed down for 3 months. Because I was quite busy to prepare interviews and exams, I had no time to dispose the problem. This weekend, I spent all of my free...