151. Reverse Words in a String

Posted 2021-03-25 wentiliangkaihua

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

 

Example 1:

Input: "the sky is blue"
Output: "blue is sky the"

Example 2:

Input: "  hello world!  "
Output: "world! hello"
Explanation: Your reversed string should not contain leading or trailing spaces.

Example 3:

Input: "a good   example"
Output: "example good a"
Explanation: You need to reduce multiple spaces between two words to a single space in the reversed string.

 

Note:

• A word is defined as a sequence of non-space characters.
• Input string may contain leading or trailing spaces. However, your reversed string should not contain leading or trailing spaces.
• You need to reduce multiple spaces between two words to a single space in the reversed string.

  class Solution {
      public String reverseWords(String s) {
             String[] arr = s.split(" ");
          StringBuilder sb = new StringBuilder();
          for(int i=arr.length-1; i>=0; i--){
              if(arr[i].length() > 0) {
                  sb.append(arr[i] + " ");
              }
          }
          
          return sb.toString().trim();
      }
  }