Leetcode 344-reverse String

The original question is as follows:

Write a function that takes a string as input and returns the string reversed.

Example:
Given s = "Hello", Return "Olleh".

Simple string flipping, directly on the code.

1      Public string reversestring (string s) {2         New StringBuilder (); 3          for (int i = s.length ()-1; I >= 0; i--) {4            sb.append (S.charat (i)); 5         }6         return  sb.tostring (); 7     }

How to achieve in-situ flip it? Because string cannot be modified, the method definition needs to be modified, and the parameter uses StringBuilder.

1      Public voidreversestringinplace (StringBuilder sb) {2Reversestringinplace (SB, 0, Sb.length ()-1);3     }4 5      Public voidReversestringinplace (StringBuilder SB,intStartintend) {6         if(Start >= End | | end > Sb.length ()-1) {7             return;8         }9          for(inti = start, j = end; I < J; i++, j--) {Ten             CharTMP =Sb.charat (i); One Sb.setcharat (I, Sb.charat (j)); A Sb.setcharat (J, TMP); -         } -}

Here's another question, how do you flip the order of words in a string, but the word itself doesn't change?

Example:
Given s = "Hello World" and return "World Hello".

WORKAROUND: Flip Each word first, then flip the entire string.

1      Public voidreversesentenceinplace (StringBuilder sb) {2         inti = 0, j = 0;3          for(; J < Sb.length (); j + +) {4             if(!Character.isletter (Sb.charat (j))) {5                 if(I <j) {6Reversestringinplace (SB, I, j-1);7                 }8i =J;9i++;Ten             } One         } A         if(I <j) { -Reversestringinplace (SB, I, j-1); -         } theReversestringinplace (SB, 0, Sb.length ()-1); -}

Reference Source: Https://github.com/pkufork/Martians/blob/master/src/main/java/com/pkufork/martians/leetcode/ReverseString344.java

Leetcode 344-reverse String