class Solution {
    // 14. Longest Common Prefix
    public String longestCommonPrefix(String[] strs) {
        if (strs == null || strs.length == 0)
            return "";

        StringBuilder sb = new StringBuilder(strs[0]);
        for (int i = 1; i < strs.length; i++) {
            while (strs[i].indexOf(sb.toString) != 0) {
                sb.deleteCharAt(sb.length() - 1);
                if (sb.length() == 0) return "";
            }
        }
        return sb.toString();
    }
}