Is unique lcci
class Solution:
def isUnique(self, astr: str) -> bool:
# solution #1
astr = sorted(astr)
for i in range (1,len(astr)):
if astr[i]==astr[i-1]:
return False
return True
# # solution # 2
# return len(set(astr))==len(astr)
## solution #3
dic = [0]*26
for i in range(len(astr)):
dic[ord(astr[i])-ord("a")] += 1
for i in range(len(dic)):
if dic[i] >1:
return False
return True