题目如下:

Implement the StreamChecker class as follows:

  • StreamChecker(words): Constructor, init the data structure with the given words.
  • query(letter): returns true if and only if for some k >= 1, the last k characters queried (in order from oldest to newest, including this letter just queried) spell one of the words in the given list.

Example:

StreamChecker streamChecker = new StreamChecker(["cd","f","kl"]); // init the dictionary.
streamChecker.query('a'); // return false
streamChecker.query('b'); // return false
streamChecker.query('c'); // return false
streamChecker.query('d'); // return true, because 'cd' is in the wordlist
streamChecker.query('e'); // return false
streamChecker.query('f'); // return true, because 'f' is in the wordlist
streamChecker.query('g'); // return false
streamChecker.query('h'); // return false
streamChecker.query('i'); // return false
streamChecker.query('j'); // return false
streamChecker.query('k'); // return false
streamChecker.query('l'); // return true, because 'kl' is in the wordlist

Note:

  • 1 <= words.length <= 2000
  • 1 <= words[i].length <= 2000
  • Words will only consist of lowercase English letters.
  • Queries will only consist of lowercase English letters.
  • The number of queries is at most 40000.

解题思路:本题真对不起hard的级别,用字典树即可解决。首先在init的时候,把words中所有word逆置后存入字典树中;在query的时候,也有逆序的方式记录所有历史query过的值,同时判断其前缀是否存在于字典树中即可。

代码如下:

class TreeNode(object):
def __init__(self, x):
self.val = x
self.childDic = {}
self.isword = False class Trie(object):
dic = {}
def __init__(self):
"""
Initialize your data structure here.
"""
self.root = TreeNode(None)
self.dic = {} def insert(self,word):
node = self.root
for i in word:
if i not in node.childDic:
node.childDic[i] = TreeNode(i)
node = node.childDic[i]
node.isword = True
def isExist(self,word):
node = self.root
for i in word:
if i in node.childDic:
node = node.childDic[i]
if node.isword == True:
return True
else:
return False class StreamChecker(object):
q = ''
def __init__(self, words):
"""
:type words: List[str]
"""
self.t = Trie()
for w in words:
self.t.insert(w[::-1]) def query(self, letter):
"""
:type letter: str
:rtype: bool
"""
#letter = letter[::-1]
self.q = letter + self.q
return self.t.isExist(self.q)

【leetcode】1032. Stream of Characters的更多相关文章

  1. 【LeetCode】158. Read N Characters Given Read4 II - Call multiple times

    Difficulty: Hard  More:[目录]LeetCode Java实现 Description Similar to Question [Read N Characters Given ...

  2. 【LeetCode】157. Read N Characters Given Read4

    Difficulty: Easy  More:[目录]LeetCode Java实现 Description The API: int read4(char *buf) reads 4 charact ...

  3. 【LeetCode】157. Read N Characters Given Read4 解题报告(C++)

    作者: 负雪明烛 id: fuxuemingzhu 个人博客:http://fuxuemingzhu.cn/ 目录 题目描述 题目大意 解题方法 直接调用 日期 题目地址:https://leetco ...

  4. 【LeetCode】1002. Find Common Characters 解题报告(Python)

    作者: 负雪明烛 id: fuxuemingzhu 个人博客: http://fuxuemingzhu.cn/ 目录 题目描述 题目大意 解题方法 字典 日期 题目地址:https://leetcod ...

  5. 【leetcode】1002. Find Common Characters

    题目如下: Given an array A of strings made only from lowercase letters, return a list of all characters ...

  6. 【leetcode】557. Reverse Words in a String III

    Algorithm [leetcode]557. Reverse Words in a String III https://leetcode.com/problems/reverse-words-i ...

  7. 【LeetCode】二叉查找树 binary search tree(共14题)

    链接:https://leetcode.com/tag/binary-search-tree/ [220]Contains Duplicate III (2019年4月20日) (好题) Given ...

  8. 【leetcode】955. Delete Columns to Make Sorted II

    题目如下: We are given an array A of N lowercase letter strings, all of the same length. Now, we may cho ...

  9. 【LeetCode】代码模板,刷题必会

    目录 二分查找 排序的写法 BFS的写法 DFS的写法 回溯法 树 递归 迭代 前序遍历 中序遍历 后序遍历 构建完全二叉树 并查集 前缀树 图遍历 Dijkstra算法 Floyd-Warshall ...

随机推荐

  1. Fedora 26 安装搜狗拼音输入法 sogoupinyin

    Fcitx 官方 wiki Fcitx GitHub Arch wiki 上关于 Fcitx 的资料 故障排除可以参考这里 Fedora 中文社区 Fedora 中文社区软件源 Fcitx (Flex ...

  2. JS 创建动态表格练习

    创建动态表格 1.1 <!DOCTYPE html> <html> <head> <meta charset="UTF-8"> &l ...

  3. CET-6 分频周计划生词筛选(Week 3)

    点我阅读 Week 3 2016.09.11 p113 manipulate + propel p114 expedition + deficit p115 all p116 envisage p11 ...

  4. 普通ACL访问控制列表

    配置OSPF R1: R2: R3: R4: 在R1上查看OSPF的学习 测试R1与R4环回接口连通性 配置普通ACL访问控制列表: 先在R4配置密码用R1与R4建立telnet建立 密码huawei ...

  5. JSP基础--EL表达式

    EL(表达式语言) 1 EL概述 1.1 EL的作用 JSP2.0要把html和css分离.要把html和javascript分离.要把Java脚本替换成标签.标签的好处是非Java人员都可以使用. ...

  6. SAP选择屏幕开发(一)(转)

    原文链接:https://blog.csdn.net/wtxhai/article/details/90632686 用户通过屏幕操作来实现与SAP的数据交互,而SAP的屏幕开发一般分为两种,一种是通 ...

  7. MyBatis-Spring的sqlSessionTemplate

    转自:http://www.cnblogs.com/yhtboke/p/5611375.html SqlSessionTemplate SqlSessionTemplate是MyBatis-Sprin ...

  8. IDEA 光标显示注释

  9. SpringBoot项目FatJar同War之间的相互转换

    目录 1.原有的项目结构 修改后的项目结构 常见的dependency的scope 1.原有的项目结构 启动类 @SpringBootApplication(exclude = {DataSource ...

  10. 使用Angular2+的内置管道格式化数据

    在简书看到一篇关于Angualr运用内置管道格式化数据的总结,感觉挺实用的,转载一下以供参考: [转载]https://www.jianshu.com/p/a8bd5a1d2c53 PS:管道是在HT ...