LeetCode（14）——Longest Common Prefix

题目：

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.

AC：

class Solution {
    public String longestCommonPrefix(String[] strs) {
        if (0 == strs.length) {
            return "";
        }
        
        int end = 0;
        char ch = 0;
        while (true) {
            for (String s : strs) {
                if (end  >= s.length()) {
                    if (0 == end) {
                        return "";
                    }
                    else {
                        return s.substring(0, end);
                    }
                }
                
                if (0 == ch) {
                    ch = s.charAt(end);
                }
                
                if (ch != s.charAt(end)) {
                    if (0 == end) {
                        return "";
                    }
                    else {
                        return s.substring(0, end);
                    }
                }
                
            }
            
            ch = 0;
            end++;
        }
        

    }
}