class Solution:
    def numUniqueEmails(self, emails: 'List[str]') -> 'int':
        accept = []
        for email in emails:
            local = email.split('@')[0]
            domain = email.split('@')[1]
            if '+' in local:
                local = local.split('+')[0]
            if '.' in local:
                local = local.replace('.','')
            result = local+domain
            if result not in accept:
                accept.append(result)
        return len(accept)

　其中：速度76ms，内存12.7M

　优化一：使用set直接去重复，使用''.join()进行字符拼接

class Solution:
    def numUniqueEmails(self, emails: 'List[str]') -> 'int':
        accept = set()
        for email in emails:
            local,domain = email.split('@')
            local = ''.join(local.split('+')[0].split('.'))
            result = local + '@' +domain
            accept.add(result)
        return len(accept)

　　速度：48ms，内存12.6M

优化二：使用map映射的方式，不用手动申请内存，可能map函数自动申请了内存，所以内存没有降下来。

class Solution:
    def numUniqueEmails(self, emails: 'List[str]') -> 'int':
        def processone(email):
            i = email.find('@')
            j = email.find('+')
            if j < i and j>0:
                return ''.join(email[:j].split('.')) + email[i:]
            elif j == 0:
                return email[i:]
            else:
                return ''.join(email[:i].split('.')) + email[i:]
        
        return len(set(map(processone,emails)))

　　速度：44ms,内存12.5M