Longest Common Prefix

be careful of the special cases(null, 0)

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.
        if(strs == null||strs.length == 0)
            return "";
        if(strs.length == 1)
            return strs[0];
        char[] mychar = strs[0].toCharArray();
        int max = mychar.length;
        for(int i = 1; i < strs.length; i++)
        {
            char[] tmp = strs[i].toCharArray();
            int tmpmax = 0;
            for(int j = 0; j < Math.min(mychar.length, tmp.length); j++)
            {
                if(mychar[j] == tmp[j])
                    tmpmax++;
                else
                    break;
            }
            max = Math.min(max,tmpmax);
        }
        return strs[0].substring(0,max);
    }
}