Leetcode151. 反转字符串中的单词

题目传送：​​https://leetcode.cn/problems/reverse-words-in-a-string/​​

运行效率：

代码如下:

class Solution {
 public String reverseWords(String s) {
     //处理特殊情况，  如果s就是一个单词
     if(!s.contains(" ")){
         return s;
     }
        //去掉左右两边多余的空格
        s = s.trim();
        Stack<String> stack = new Stack<>();
        int left = 0;
        int right = left + 1;
        while (right < s.length()) {
            //找到单词的尾部
            while (right < s.length() && s.charAt(right) != ' ') {
                right++;
            }
            //然后就可以截取单词
            String word = s.substring(left, right);
            stack.push(word);
            s = s.substring(right).trim();
            left=0;
            right=left+1;
              if(right==s.length()){
                //然后就可以截取单词
                 word = s.substring(left, right);
                stack.push(word);
                s = s.substring(right).trim();
            }
        }
        StringBuilder stringBuilder = new StringBuilder();
        while (!stack.isEmpty()) {
            String pop = stack.pop();
            stringBuilder.append(pop).append(" ");
        }
        return stringBuilder.toString().trim();
    }
}