【LeetCode】Longest Common Prefix

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

java code : 预处理出最短串与任意一字符串的公共前缀，用StringBuilder保存，再去遍历剩余字符串，从尾处开始推。

复杂度O(m * n) m : length of the arrays, n ：length of the prefix

public class Solution {
public String longestCommonPrefix(String[] strs) {
// IMPORTANT: Please reset any member data you declared, as
// the same Solution instance will be reused for each test case.
int numofstr = strs.length;
if(numofstr < 1)
return new String("");
if(numofstr == 1)
return strs[0];
StringBuilder res = new StringBuilder();
String minlen = strs[0];
int indexmin = 0;
for(int i = 1; i < numofstr; i++)
{
if(minlen.length() > strs[i].length())
{ minlen = strs[i];indexmin = i;}
}
String str1 = strs[0];
String str2 = strs[1];
int index2 = 1;
if(minlen.equals(strs[0]))
{
str1 = minlen;
str2 = strs[1];
}
else
{
str1 = minlen;
str2 = strs[0];
index2 = 0;
}
int i = 0, j = 0;
while(i < str1.length() && j < str2.length())
{
if(str1.charAt(i) == str2.charAt(j))
{
res.append(str1.charAt(i));
i++;j++;
continue;
}
break;
}
if(numofstr < 3 || res.length() == 0)
return res.toString();
for(int k = 0; k < numofstr; k++)
{
if(k == indexmin || k == index2)
continue;
int len = res.length();
String cur = strs[k];
while(len > 0 && (cur.charAt(len - 1) != res.charAt(len - 1)))
{
res.deleteCharAt(len - 1);
len--;
}

}
return res.toString();

}
}