LeetCode -- Longest Common Prefix

Question:

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

Analysis:

写一个函数找到一个字符串数组的最长公共前缀。

思路：依次两两比较，用短的前缀更新比较长的前缀，一直到数组的末尾。

Answer：

public class Solution {
public static String longestCommonPrefix(String[] strs) {
if(strs.length == 0)
return "";
if(strs.length == 1)
return strs[0];
char[] res = strs[0].toCharArray();
for(int i=1; i<strs.length; i++) {
char[] ch1 = strs[i-1].toCharArray();
char[] ch2 = strs[i].toCharArray();
char[] ch12 = getCommon(ch1, ch2);
//System.out.println(ch12[0]);
if(ch12.length == 1 && ch12[0] == '\0')
return "";
if(ch12.length <= res.length) {
res = ch12;
}
}
return new String(res);
}
public static char[] getCommon(char[] ch1, char[] ch2) {
int shorter = ch1.length <= ch2.length ? ch1.length : ch2.length;
char[] prefix = new char[shorter];
int common = 0;
for(int j=0; j<shorter; j++) {
if(ch1[j] == ch2[j]) {
common++;
prefix[j] = ch1[j];
}
else
break;
}
char[] prefix1 = new char[common];
for(int i=0; i<common; i++)
prefix1[i] = prefix[i];
return prefix1;
}
}