LeetCode | Reverse Words in a String-优快云博客

本文链接：https://blog.youkuaiyun.com/perfect8886/article/details/20833685

本文介绍了一种使用Java实现的方法，该方法可以将输入字符串中的单词顺序进行反转，同时处理了空格和多余空格的问题。

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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.

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);
	}
}