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摘要： 算法描述： Given a binary tree, return the zigzag level order traversal of its nodes' values. (ie, from left to right, then right to left for the next leve 阅读全文

摘要： 算法描述： Given a binary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level). For example:Given binary t 阅读全文

摘要： 算法描述： Given a binary tree, determine if it is a valid binary search tree (BST). Assume a BST is defined as follows: The left subtree of a node contain 阅读全文

摘要： 算法描述： Given n, how many structurally unique BST's (binary search trees) that store values 1 ... n? Example: 解题思路：动态规划，f(n) = f(0)*f(n-1) + f(1)*f(n-2) 阅读全文

摘要： 算法描述： Given an integer n, generate all structurally unique BST's (binary search trees) that store values 1 ... n. Example: 解题思路：深度优先，递归求解。 阅读全文

摘要： 算法描述： Given a binary tree, return the inorder traversal of its nodes' values. Example: Follow up: Recursive solution is trivial, could you do it itera 阅读全文

摘要： 算法描述： Given a string containing only digits, restore it by returning all possible valid IP address combinations. Example: 解题思路：题目要求所有可能的结果，首先想到回溯法。重点有 阅读全文

摘要： 算法描述： Reverse a linked list from position m to n. Do it in one-pass. Note: 1 ≤ m ≤ n ≤ length of list. Example: 解题思路：链表题，首先要画图。四个指针，头指针，前指针，临时指针。 阅读全文

摘要： 算法描述： A message containing letters from A-Z is being encoded to numbers using the following mapping: Given a non-empty string containing only digits, 阅读全文

摘要： 算法描述： Given a collection of integers that might contain duplicates, nums, return all possible subsets (the power set). Note: The solution set must not 阅读全文