字符串-Reverse Words in a String（翻转字符串）

来源：互联网发布：linux patch 编辑：程序博客网时间：2024/05/17 03:32

问题描述：

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

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

Update (2015-02-12):
For C programmers: Try to solve it in-place in O(1) space.

思考：

关键在于对空格的剔除和对字符串的索引的把握，思路就是使用一个result字符串类累加保存结果，把顺序寻找的字符串添加在result的0位置上，那么后面的索引向后向后全部移动新字符串长度。

代码（java）：

public class Solution {    public String reverseWords(String s) {                int begin = 0;          int end   = 0;                 if(s==null) {              return s;          }                   while(begin<s.length()&&s.charAt(begin)==' ') {              begin++;          }          if(begin==s.length()) {              return "";          }                    if(s.length()<=1) {              return s;          }          StringBuilder result = new StringBuilder("");          while(begin<s.length()&&end<s.length()) {              while(begin<s.length()&&s.charAt(begin)==' ') {                  begin++;              }              if(begin==s.length()) {                  break;              }              end = begin + 1;              while(end<s.length()&&s.charAt(end)!=' ') {                  end++;              }              if(result.length()!=0) {                  result.insert(0," ");              }              if(end<s.length()) {                  result.insert(0,s.substring(begin,end));              } else {                  result.insert(0,s.substring(begin,end));                  break;              }              begin = end + 1;          }          return result.toString();      }}

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