【Java】557. Reverse Words in a String II

因为要通过空格把字符串分割成单词，所以第一反应是用Java。

新学到的知识：StringBuilder和trim() trim():去掉字符串首尾的空格。 String,StringBuilder以及StringBuffer这三个类之间区别主要是在两个方面，即运行速度和线程安全。

题目：

Given a string, you need to reverse the order of characters in each word within a sentence while still preserving whitespace and initial word order.

Example 1:

Input: "Let's take LeetCode contest" Output: "s'teL ekat edoCteeL tsetnoc"

Note:In the string, each word is separated by single space and there will not be any extra space in the string.

解答： class Solution { public String reverseWords(String s) { String[] array = s.split(" "); StringBuilder output = new StringBuilder();//StringBuilder是字符串变量，效率比String高。String是字符串常量。 int arrlen = array.length; for(int i=0; i<arrlen; i++) array[i] = new StringBuilder(array[i]).reverse().toString(); for(int i=0; i<arrlen; i++) { output.append(array[i]); output.append(" "); } return output.toString().trim(); } }