LeetCode 14. Longest Common Prefix

https://leetcode.com/problems/longest-common-prefix/

題目：

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: strs = ["flower","flow","flight"]
Output: "fl"
        
Example 2:

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


Constraints:
1 <= strs.length <= 200
0 <= strs[i].length <= 200
strs[i] consists of only lower-case English letters.

解答：

使用 JAVA 語言

一開始想用字串來解此題，第一個一直 substring 減少 去和 第二個比對

後來發現，假如第一個字很長，第二個字比較短就會有問題

後來改成用單獨字去比對，再用for迴圈 + 遞迴比較穩定一點，不會有少字的問題

class Solution {
    public String longestCommonPrefix(String[] strs) {
        if (strs.length == 1) return strs[0];

        StringBuffer temp = new StringBuffer();

        char[] a = strs[0].toCharArray();
        int firstLength = a.length;

        char[] a2 = strs[1].toCharArray();
        int firstLength2 = a2.length;

        if (firstLength>0 && firstLength2>0){
            for (int i=0; i<firstLength  &&  i<firstLength2; i++){
                if (a[i] != a2[i]){
                    break;
                } else {
                    temp.append(a[i]);
                }
            }
        }

        String[] newStrs = new String[strs.length-1];

        for (int i=0; i<strs.length-1; i++){
            if (i==0)
                newStrs[0] = temp.toString();
            else
                newStrs[i] = strs[i+1];
        }
        return longestCommonPrefix(newStrs);
    }
}