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: strs = ["flower","flow","flight"]
Output: "fl"

Example 2:

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

很聪明的做法，先假设第一个string是Longest Common Prefix， 跟后面的string一个一个对比，不match就删除最后一个字符，until it matches。 

class Solution {
    public String longestCommonPrefix(String[] strs) {
        String pre = strs[0];

        for(int i = 1; i < strs.length; i++){
            while(!strs[i].startsWith(pre)){
                pre = pre.substring(0, pre.length() - 1);
            }
        }

        return pre;
    }
}