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 / 3return
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 / 3return
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 parentchild 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 nonempty 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 ...