#include <bits/stdc++.h>
using namespace std;
class Solution {
    public :
        int solve (string s,int k){
            vector <int> freq(26);
            
            int l=0;int r=0;
            int offset=(int)'a';
            int ans=0;
            while (r<s.size()){
                if (r-l<k-1){   
                   freq[s[r]-offset]++;
                    r++;             
                }else if (r-l==k-1){
                    freq[s[r]-offset]++;
                    r++;
                    bool t=true;
                    for (int x:freq){
                        if (x>1){
                          t=false;
                        }
                    }
                    t?ans+=1:ans=ans;
                    
                }else if (r-l>k-1){
                    freq[s[l]-offset]--;
                    l++;
                }
                
            }
            return ans;
        }
};

int main () {
    string s="abcdefhijklmnopqrstuvwxyz";
    int k=5;
    Solution* sol=new Solution();
    cout<<sol->solve(s,k);
}

"""

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"))