0014-longest-common-prefix.java

class Solution {
    public String longestCommonPrefix(String[] strs) {
        StringBuilder res = new StringBuilder();
        for(int i = 0; i < strs[0].length(); i++) {
            for(String s: strs)
                if(i == s.length() || s.charAt(i) != strs[0].charAt(i))
                    return res.toString();
            res.append(strs[0].charAt(i));
        }
        return res.toString();
    }
}