Q14: Longest Common Prefix

 class Solution {
        public String longestCommonPrefix(String[] strs) {
           
            if (strs.length == 0 || strs == null)
                return "";
            
// j = counter for chars
// i = counter for words
            
            StringBuffer prefix = new StringBuffer("");

            for(int j=0; j<strs[0].length(); j++) {

                for(int i=1; i<strs.length; i++) {
                    if (j<strs[i].length()) {
                        if (strs[0].charAt(j) != strs[i].charAt(j))
                            return String.valueOf(prefix);
                    }    
                    else if (j == strs[i].length()) 
                        return String.valueOf(prefix);
                }

                prefix.append(strs[0].charAt(j));

            }

            return String.valueOf(prefix);

        }
 }