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.
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.
原问题链接:https://leetcode.com/problems/reverse-words-in-a-string/
问题分析
这个问题的思路其实比较简单,因为它只是要把一个字符串里所有非空格的词语顺序给倒过来。那么我们就有这么一个基本的思路,首先将这个串按照空格给划分成多个非空的字符串。然后从后往前将字符串加入到一个StringBuilder中。最后去除两头的空格。当然,问题的要求里提到每个词语之间要有一个空格作为间隔,在实现的时候要注意这一点。
详细的代码实现如下:
public class Solution { public String reverseWords(String s) { String[] words = s.split("\\s+"); StringBuilder builder = new StringBuilder(); for(int i = words.length - 1; i >= 0; i--) builder.append(words[i] + " "); return builder.toString().trim(); } }