Reverse Linked List II Reverse a linked list from position m to n. Do it in-place and in one-pass. For example: Given 1->2->3->4->5->NULL, m = 2 and n = 4, return 1->4->3->2->5->NULL. Note: Given m, n satisfy the following condition: 1 ≤ m ≤ n ≤ length of list. tag: […]
Binary Tree Inorder Traversal Given a binary tree, return the inorder traversal of its nodes’ values. For example: Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [1,3,2]. Note: Recursive solution is trivial, could you do it iteratively? confused what “{1,#,2,3}” means? > read more on how binary tree […]
Valid Palindrome Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases. For example, “A man, a plan, a canal: Panama” is a palindrome. “race a car” is not a palindrome. Note: Have you consider that the string might be empty? This is a […]
Copy List with Random Pointer A linked list is given such that each node contains an additional random pointer which could point to any node in the list or null. Return a deep copy of the list. tag: hashtable, linked-list 虽然被标记为hard，但代码不长。 问题关键是，在拷贝完next指针后，要根据原来链表中的random的地址，找到新建的链表中对应的node的地址，这里我们用一个hashtable来实现，在拷贝next指针时，将对应关系记录下来。 空间复杂度o(n)，时间复杂度o(n)。 /** * Definition for singly-linked list with […]
