/*
Leetcode 75

Given an input string s, reverse the order of the words.

A word is defined as a sequence of non-space characters. The words in s will be separated by at 
least one space.

Return a string of the words in reverse order concatenated by a single space.

Note that s may contain leading or trailing spaces or multiple spaces between two words. 
The returned string should only have a single space separating the words. Do not include any extra spaces.

Example 1:

Input: s = "the sky is blue"
Output: "blue is sky the"
Example 2:

Input: s = "  hello world  "
Output: "world hello"
Explanation: Your reversed string should not contain leading or trailing spaces.
Example 3:

Input: s = "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.
 
Constraints:

1 <= s.length <= 104
s contains English letters (upper-case and lower-case), digits, and spaces ' '.
There is at least one word in s.
 
Follow-up: If the string data type is mutable in your language, 
can you solve it in-place with O(1) extra space?
*/

package ReverseWords

import (
	"strings"
)

func ReverseTokens(s string) string {
	words := strings.Fields(s)
	var tokens []string
	for _, st := range words {
		if st != "" {
			tokens = append(tokens, st)
		}
	}
	for i, j := 0, len(tokens)-1; i < j; i, j = i+1, j-1 {
        tokens[i], tokens[j] = tokens[j], tokens[i]
    }
	return strings.Join(tokens, " ")
}