"""

Question Denoscription
    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.
    
    
    "a good   example"
["a","good","example"]
      L  R
 
 
 [example,"good","a"]


"""

#will s will split
#variables left->0 rght ->len(splited)-1
#will have  a while l<L    left+=1 righ-=1 


def revercing_word(s):
    words=[] 
    for word in s.split(" "):
        if word:
            words.append(word)
    
    left=0
    right=len(words)-1
    
    
    while left<right:
        words[left],words[right]= words[right],words[left]
        left+=1
        right-=1
        
    return " ".join(words)
print(revercing_word("hello world"))