Given a string, you need to reverse the order of characters in each word within a sentence while still preserving whitespace and initial word order.

Example 1:

Input: "Let‘s take LeetCode contest"
Output: "s‘teL ekat edoCteeL tsetnoc"

Note: In the string, each word is separated by single space and there will not be any extra space in the string.

題目標簽：String

　　題目給了我們一串string，讓我們把每一個word 給reverse一下。

　　設p1 和 p2，每一次讓p2 找到 “ ” space，然後 reverse p1 和 p2 之間的 word，然後更新p1 和 p2 的值。

　　具體請看code。

Java Solution:

Runtime beats 96.43%

完成日期：05/31/2018

關鍵詞：Two pointers

關鍵點：反轉p1 和 p2 之間的 word

 1 class Solution 
 2 {
 3     public
 
 String reverseWords(String s) 
 4     {
 5         char [] arr = s.toCharArray();
 6         int p1 = 0;
 7         int p2 = 0;
 8         
 9         while(p1 < arr.length)
10         {
11             // let p2 find the space
12             while(p2 < arr.length && arr[p2] != ‘ ‘)
 
13                 p2++;
14             
15             // once p2 find the space, do reverse between p1 and p2
16             int left = p1;
17             int right = p2 - 1;
18             
19             while(left < right)
20             {
21                 char temp = arr[left];
22                 arr[left] = arr[right];
23                 arr[right] = temp;
24                 
25                 left++;
26                 right--;
27             }
28             
29             // reset p1 p2
30             p1 = p2 + 1;
31             p2++;
32             
33         }
34         
35         return new String(arr);
36     }
37     
38 
39 }

參考資料：n/a

LeetCode 題目列表 - LeetCode Questions List

題目來源：https://leetcode.com/

LeetCode 557. Reverse Words in a String III (反轉字符串中的單詞 III)