14.最长公共前缀

输入：strs = ["flower","flow","flight"]
输出："fl"

输入：strs = ["dog","racecar","car"]
输出：""
解释：输入不存在公共前缀。

public static String longestCommonPrefixSolution(String[] strs) {
        if (strs == null || strs.length == 0) {
            return "";
        }
        String str = strs[0];
        for (int i = 1; i < strs.length; i++) {
            int index = 0;
            while (index < Math.min(str.length(), strs[i].length()) && str.charAt(index) == strs[i].charAt(index)) {
                index++;
            }
            str = str.substring(0, index);
        }
        return str;
    }