151. Reverse Words in a String.cpp

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