Leetcode longest public prefix

Title Description ：

Write a function to find the longest common prefix in the string array .

If no common prefix exists , Returns an empty string "".

Examples ：

Example 1：

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

Example 2：

Input ：strs = ["dog","racecar","car"]
Output ：""
explain ： Input does not have a common prefix .

Tips ：

    1 <= strs.length <= 200
    0 <= strs[i].length <= 200
    strs[i] It's only made up of lowercase letters

Java Program ：

class Solution {
    public String longestCommonPrefix(String[] strs) {
        if (strs == null || strs.length == 0) {
            return "";
        }
        String prefix = strs[0];
        int count = strs.length;
        for (int i = 1; i < count; i++) {
            prefix = longestCommonPrefix(prefix, strs[i]);
            if (prefix.length() == 0) {
                break;
            }
        }
        return prefix;
    }

    public String longestCommonPrefix(String str1, String str2) {
        int length = Math.min(str1.length(), str2.length());
        int index = 0;
        while (index < length && str1.charAt(index) == str2.charAt(index)) {
            index++;
        }
        return str1.substring(0, index);
    }
}