557. Reverse Words in a String III.java

E
tags: String

给一个String, 里面的Word被single space split开来, 目的是reverse里面所有的Word, 但preserve Word 和 space order.

#### Reverse function
- Reverse Words in a String II 的降级版, 去掉第一个overall reverse就好了

```
/*
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.


*/

class Solution {
    public String reverseWords(String s) {
        if (s == null || s.length() <= 1) {
            return s;
        }
        char[] str = s.toCharArray();
        int start = 0;
        for (int i = 0; i < str.length; i++) {
            if (str[i] == ' ') {
                reverse(str, start, i - 1);
                start = i + 1;
            } else if (i == str.length - 1) {
                reverse(str, start, i);
            }
        }//end for
        
        return String.valueOf(str);
    }
    
    public void reverse(char[] s, int start, int end) {
        while (start < end) {
            char temp = s[start];
            s[start] = s[end];
            s[end] = temp;
            start++;
            end--;
        }
    }
}
```