Leetcode problem no. 151

class Solution {
public:
    string reverseWords(string s) {
        string result;
        int i = 0, n = s.length();
        
        while(i < n){
            while(i < n && s[i] == ' ') i++;
            
            if(i >= n) break;
            
            int j = i;
    
            while(j < n && s[j] != ' ')
                j++;
            
            string sub = s.substr(i, j-i);
            
            if(result.length() == 0) result = sub;
            
            else result = sub + " " + result;
            
            i = j+1;
        }
        
        return result;
    }
};