LeetCode | Reverse Words in a String

题目

Given an input string, reverse the string word by word.

For example,
Given s = "the sky is blue",
return "blue is sky the".

click to show clarification.

• What constitutes a word
  A sequence of non-space characters constitutes a word.
• Could the input string contain leading or trailing spaces
  Yes. However, your reversed string should not contain leading or trailing spaces.
• How about multiple spaces between two words
  Reduce them to a single space in the reversed string. 分析

  正统的做法就是自己去逐个找到每个单词，从前往后还是从后往前其实都差不多，都要翻转：要么是翻转字母（从后往前）、要么翻转单词（从前往后）。

  这里给出的是用java自带的split方法，帮助我们以“ ”进行切割，代码看上去会比较简洁明了。

  代码

  public class ReverseWordsInAString {
  	public String reverseWords(String s) {
  		if (s == null || s.length() == 0) {
  			return "";
  		}
  
  		String[] array = s.split(" ");
  		StringBuilder sb = new StringBuilder();
  		for (int i = array.length - 1; i >= 0; --i) {
  			if (!array[i].equals("")) {
  				sb.append(array[i]).append(" ");
  			}
  		}
  		return sb.length() == 0   "" : sb.substring(0, sb.length() - 1);
  	}
  }