Reverse Words in a String 翻转一个字符串里的单词顺序 @LeetCode

关注

原创最新推荐文章于 2026-06-23 16:45:31 发布 2.6k 阅读 AI 写同款· GEO 优化 ›

151. 反转字符串中的单词（力扣LeetCode）想一下，我们将整个字符串都反转过来，那么单词的顺序指定是倒序了，只不过单词本身也倒序了，那么再把单词反转一下，单词不就正过来了。移除前导空格和多余空格：快指针 fast 用于跳过前导空格和连续的空格，而慢指针 slow 用于构建没有多余空格的新字符串。这个函数实现了题目要求的功能，使用了原地操作（没有使用额外的存储空间），然后完成单词的反转，并且在单词之间只保留一个空格。版本一的代码是一般的思考过程，就是先移除字符串前的空格，再移除中间的，再移除后面部分。单词是由非空格字符组成的字符串。阅读详情

LeetCode新题，但是比较简单，直接用栈即可

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.

public class Solution {
    public String reverseWords(String s) {
        if(s.length() == 0) {
            return s;
        }
        Stack<String> stack = new Stack<String>();
        String[] ss = s.split("\\s+");
        for(String word : ss) {
            stack.push(word);
        }
        StringBuilder sb = new StringBuilder();
        while(!stack.isEmpty()) {
            sb.append(stack.pop()).append(" ");
        }
        return sb.toString().trim();
    }
}