LeetCode--To Lower Case && Remove Outermost Parentheses (Easy)
709. To Lower Case(Easy)#
Implement function ToLowerCase() that has a string parameter str, and returns the same string in lowercase.
Example 1:
Input: "Hello"
Output: "hello"
Example 2:
Input: "here"
Output: "here"
Example 3:
Input: "LOVELY"
Output: "lovely"
Note:
there are many other characters,such as '&".
solution##
class Solution {
public String toLowerCase(String str) {
StringBuilder s = new StringBuilder();
for (int i=0; i<str.length(); i++)
{
if ('a' <= str.charAt(i) && str.charAt(i) <='z')
s.append(str.charAt(i));
else if ('A' <= str.charAt(i) && str.charAt(i) <='Z')
s.append((char)(str.charAt(i) - 'A' + 'a'));
else
s.append(str.charAt(i));
}
return s.toString();
}
}
总结##
此题思路很简单,遍历给定字符串,如果字母为大写字母,则变为小写字母后用一个字符串变量存起来,否则直接将小写字母或其他字符存起来。
Notes:
1.用StringBuilder类更省空间;
2.两个字符相加减得到的结果为int型数值,要转为字符必须用(char)强制转换,比如char c = (char)97,得到的结果为c=a;
3.字符拼接一般用StringBuilder类的append()方法;
1021. Remove Outermost Parentheses (Easy)#
A valid parentheses string is either empty (""), "(" + A + ")", or A + B, where A and B are valid parentheses strings, and + represents string concatenation. For example, "", "()", "(())()", and "(()(()))" are all valid parentheses strings.
A valid parentheses string S is primitive if it is nonempty, and there does not exist a way to split it into S = A+B, with A and B nonempty valid parentheses strings.
Given a valid parentheses string S, consider its primitive decomposition: S = P_1 + P_2 + ... + P_k, where P_i are primitive valid parentheses strings.
Return S after removing the outermost parentheses of every primitive string in the primitive decomposition of S.
Example 1:
Input: "(()())(())"
Output: "()()()"
Explanation:
The input string is "(()())(())", with primitive decomposition "(()())" + "(())".
After removing outer parentheses of each part, this is "()()" + "()" = "()()()".
Example 2:
Input: "(()())(())(()(()))"
Output: "()()()()(())"
Explanation:
The input string is "(()())(())(()(()))", with primitive decomposition "(()())" + "(())" + "(()(()))".
After removing outer parentheses of each part, this is "()()" + "()" + "()(())" = "()()()()(())".
Example 3:
Input: "()()"
Output: ""
Explanation:
The input string is "()()", with primitive decomposition "()" + "()".
After removing outer parentheses of each part, this is "" + "" = "".
Note:
S.length <= 10000
S[i] is "(" or ")"
S is a valid parentheses string
solution##
class Solution {
public String removeOuterParentheses(String S) {
StringBuilder s = new StringBuilder();
int k = 0;
for (int i=0; i<S.length(); i++)
{
if (S.charAt(i) == '(')
{
if (k > 0)
s.append('(');
k++;
}
if (S.charAt(i) == ')')
{
k--;
if (k > 0)
s.append(')');
}
}
return s.toString(); //return a string
}
}
总结##
此题我最初的想法是用栈,后来发现只需要用栈的思想就够了,只需用一个计数器k和一个字符串变量s。当遇到左括号时,先判断k>0是否成立,如果成立,则将左括号存入字符串s,否则什么都不做,随后计数器k++;当遇到右括号时,先计数器k--,再判断k>0是否成立,如果成立,则将右括号存入字符串s,否则什么都不做。
Notes:
1.此题又是用StringBuilder类进行字符连接,返回值需要用toString()方法转为字符串。
LeetCode--To Lower Case && Remove Outermost Parentheses (Easy)的更多相关文章
- LeetCode 1021. 删除最外层的括号(Remove Outermost Parentheses)
1021. 删除最外层的括号 1021. Remove Outermost Parentheses 题目描述 有效括号字符串为空 ("")."(" + A + ...
- 【Leetcode_easy】1021. Remove Outermost Parentheses
problem 1021. Remove Outermost Parentheses 参考 1. Leetcode_easy_1021. Remove Outermost Parentheses; 完
- 【leetcode】1021. Remove Outermost Parentheses
题目如下: A valid parentheses string is either empty (""), "(" + A + ")", ...
- 【LeetCode】1021. Remove Outermost Parentheses 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 遍历 日期 题目地址:https://leetcod ...
- [Swift]LeetCode1021. 删除最外层的括号 | Remove Outermost Parentheses
A valid parentheses string is either empty (""), "(" + A + ")", or A + ...
- LeetCode.1021-删除最外面的括号(Remove Outermost Parentheses)
这是小川的第380次更新,第408篇原创 01 看题和准备 今天介绍的是LeetCode算法题中Easy级别的第242题(顺位题号是1021).有效的括号字符串为空(""),&qu ...
- Leetcode 1021. Remove Outermost Parentheses
括号匹配想到用栈来做: class Solution: def removeOuterParentheses(self, S: str) -> str: size=len(S) if size= ...
- LeetCode #1021. Remove Outermost Parentheses 删除最外层的括号
https://leetcode-cn.com/problems/remove-outermost-parentheses/ Java Solution class Solution { public ...
- [LeetCode] To Lower Case 转为小写
Implement function ToLowerCase() that has a string parameter str, and returns the same string in low ...
随机推荐
- Thinking in Java,Fourth Edition(Java 编程思想,第四版)学习笔记(十一)之Holding Your Objects
To solve the general programming problem, you need to create any number of objects, anytime, anywher ...
- Python中关于第三方库的补充
Python语言的强大之处在于它的开源.正是因为它的开源,产生了成百上千的第三方库,涵盖了计算机的几乎所有的方向.第三方库的安装也并不是特别的复杂,通过在cmd中使用pip命令可以安装几乎所有的库,但 ...
- vue+element-ui中引入阿里播放器
1.在public文件下的index.html文件中插入以下代码: <link rel="stylesheet" href="https://g.alicdn.co ...
- mysql 使用记录
修改 mysql 数据库密码 mysqladmin -u username -h host_name password -P <port> "new_password" ...
- pytorch GPU训练好的模型使用CPU加载
torch.load('tensors.pt') # 把所有的张量加载到CPU中 torch.load('tensors.pt', map_location=lambda storage, loc: ...
- 小程序里json字符串转json对象需注意的地方
一.JSON字符串转换为JSON对象 要使用上面的str1,必须使用下面的方法先转化为JSON对象: //由JSON字符串转换为JSON对象 var obj = eval('(' + str + ') ...
- EVE模拟器的配置
(注:本文整理自达叔的EVE模拟器使用说明https://blog.51cto.com/dashu666/1971728) 基础部署篇 所需要准备的东西: 1.VMWare (虚拟化软件,用来承载模拟 ...
- Inno Setup打包之先卸载再安装
使用Inno Setup打包程序之后,如果想要在安装前先卸载,那么需要加下面代码,需要注意的是红色标注的改为你们自己的.网上看到有些说_is1前面用AppName,但是我这边验证不行. [Setup] ...
- 消息中间件metaq
消息中间件metaq安装并注册到zookper集群 项目地址 https://github.com/killme2008/Metamorphosis Memorphosis是一个消息中间件,它是lin ...
- Vue3.0新版API之composition-api入坑指南
关于VUE3.0 由于vue3.0语法跟vue2.x的语法几乎是完全兼容的,本文主要介绍了如何使用composition-api,主要分以下几个方面来讲 使用vite体验vue3.0 composit ...