Leetcode-14. 最长公共前缀

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

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

class Solution {
    public String longestCommonPrefix(String[] strs) {
        StringBuilder r = new StringBuilder();
        if (strs.length == 0) {
            return "";
        }
        if (strs.length == 1) {
            return strs[0];
        }
        String s = strs[0];
        for (String str : strs) {
            while (!str.startsWith(s)) {
                if (s.length() == 1) {
                    return "";
                }
                s = s.substring(0, s.length() - 1);
            }
        }
        return s;
    }
}