LeetCode 14: Longest Common Prefix

string CommonPrefix(string str1,string str2)
{
int len_1=str1.length();
int len_2=str2.length();

int min_len=len_1>len_2 ? len_2:len_1;

string s="";
for(int i=0;i<min_len;++i)
{
if (str1[i]==str2[i])
s+=str1[i];
else
break;
}
return s;
}

string longestCommonPrefix(vector<string>& strs)
{
if (strs.size() == 0)
return "";
string s=strs[0];
for (int i=1;i<strs.size();++i)
{
s=CommonPrefix(s,strs[i]);
if (s=="")
break;
}
return s;
}