Reverse Words in a string@leetcode

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

For example,
Given s = "the sky is blue",
return "blue is sky the".

click to show clarification.

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.

Have you been asked this question in an interview?

The algorithm for this problem is easy to come up with. We can just reverse every single words in the string, then reverse the whole string. However, we got to take care of the corner cases. For example, the beginning and tail are spaces and only one space is allowed between words. So we have to reduce the spaces if there are more than just one and to take care of the spaces in both begin and end.

Be aware that, using char *s and string. The elements in container string is const char, we can't convert the elements in char *s to string. Also, the operations of string container are mostly  work for string, but not single elements.

Here, we need to use, string.push_back(), reverse(s.begin(), s.end()), append(str).

Javascript to crack the string manipulation is very neat. Here is the code.

If you are new to JS, you might need to know a few basic JS functions.

1. split() : to split a string into substrings and you will need to define a separator for it.
For example, str.split(' '); str = "Hello World!" split string is an array which is [Hello, World!].

2. filter() : filter is to filter a string due to some rules. And the rules is defined by a function in it. filter(Boolean) is used to filter falsy, null etc. elements.

3. join() : to join the substrings together as a string with something.