def find(self, value):
"""
Find if there exists any pair of numbers which sum is equal to the value.
:type value: int
:rtype: bool
"""
dic = {}
for i in range(len(self.list)):
if value-self.list[i] in dic:
return True
else:
dic[self.list[i]]=i
return False
1 设计twosum用hashtable的时候，dic[self.list[i]]=i，这里需要把value当做key，i当做value，这是因为用target-value的时候，是看这个value是不是在dic里。if value-self.list[i] in dic:这句code是看值是否在dic里，所以需要做上述调换
