题目描述：
Given an array of n positive integers and a positive integer s, find the minimal length of a subarray of which the sum ≥ s. If there isn't one, return 0 instead.
For example, given the array [2,3 ...
归档 2015
[LeetCode]Minimum Size Subarray Sum
[LeetCode]Implement Trie (Prefix Tree)
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LeetCode.
题目描述：
Implement a trie with insert, search, and startsWith methods.
Note:
You may assume that all inputs are consist of lowercase letters a-z.
题目大意：
实现字典树，包含插入，查找和前缀查找方法。
注意：
你可以假设所有的输入只包含小写字母a-z
解题思路：
本题考查字典树数据结构的基础知识。
Trie使用孩子表示法存储，TrieNode为字典树的节点，包含属性childs和isWord。
其中childs为dict，存储当前节点的后代节点；isWord为布尔值，表示当前节点是否存储了一个单词。
Python代码：
class ...
[LeetCode]Course Schedule
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LeetCode.
题目描述：
There are a total of n courses you have to take, labeled from 0 to n - 1.
Some courses may have prerequisites, for example to take course 0 you have to first take course 1, which is expressed as ...
[LeetCode]Reverse Linked List
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LeetCode.
题目描述：
Reverse a singly linked list.
Hint:
A linked list can be reversed either iteratively or recursively. Could you implement both?
题目大意：
单链表逆置
提示：
用递归和迭代方式分别实现。
解题思路：
链表基本操作，递归方式参考：https://leetcode.com/discuss/34474/in-place-iterative-and-recursive-java-solution
Python代码：
迭代版本：
# Definition for singly-linked list ...
[LeetCode]Isomorphic Strings
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LeetCode.
题目描述：
Given two strings s and t, determine if they are isomorphic.
Two strings are isomorphic if the characters in s can be replaced to get t.
All occurrences of a character must be replaced with another character while preserving ...