```
class Solution(object):
def longestCommonPrefix(self, strs):
"""
:type strs: List[str]
:rtype: str
"""
if len(strs) == 0:
return ""
strs.sort()
s1 = strs[0]
s2 = strs[len(strs)-1]
if s1 and s2 and s1[0] != s2[0]:
return ""
i=0
j=0
c=0
while i < len(s1) and j < len(s2):
if s1[i] == s2[j]:
c += 1
i += 1
j += 1
else:
return s1[:c]
return s1[:c]
```