leetcode 14. Longest Common Prefix

Write a function to find the longest common prefix string amongst an array of strings.

If there is no common prefix, return an empty string "".

Example 1:

Input: ["flower","flow","flight"]
Output: "fl"

Example 2:

Input: ["dog","racecar","car"]
Output: ""
Explanation: There is no common prefix among the input strings.

Note:

All given inputs are in lowercase letters a-z.

 

唉。。其实是不难的一道题，但是一开始没反应过来prefix是前缀的意思，卡了好久。

学到一个新用法 indexOf 用来检索字符串

class Solution {
    public String longestCommonPrefix(String[] strs) {
        if(strs.length == 0) return "";
        String s1 = strs[0];
        for(int i=0; i< strs.length; i++) {
            while(strs[i].indexOf(s1) != 0) {
                s1 = s1.substring(0,s1.length()-1);
            }
        }
        return s1;
    }
}