Q557 Reverse Words in a String III

Reverse Words in a String III

Question

Given a string, you need to reverse the order of characters in each word within a sentence while still preserving whitespace and initial word order.

Example 1:

Input: "Let's take LeetCode contest" Output: "s'teL ekat edoCteeL tsetnoc"

Note:

In the string, each word is separated by single space and there will not be any extra space in the string.

Approach 1: Canonical Form

Intuition and Algorithm

For each email address, convert it to the canonical address that actually receives the mail. This involves a few steps:

• Separate the email address into a local part and the rest of the address.
• If the local part has a '+' character, remove it and everything beyond it from the local part.
• Remove all the zeros from the local part.
• The canonical address is local + rest.

After, we can count the number of unique canonical addresses with a Set structure.

class Solution(object):
    def numUniqueEmails(self, emails):
        seen = set()
        for email in emails:
            local, domain = email.split('@')
            if '+' in local:
                local = local[:local.index('+')]
            seen.add(local.replace('.','') + '@' + domain)
        return len(seen)


def main():
    Emails=["test.email+alex@leetcode.com",
            "test.e.mail+bob.cathy@leetcode.com",
            "testemail+david@lee.tcode.com"]
    solution=Solution().numUniqueEmails(Emails)
    print(solution)


if __name__ == "__main__":
    main()

Complexity Analysis

• Time Complexity: O(n), where n is the total content of emails.
• Space Complexity: O(n).
• Runtime: 28 ms, faster than 99.72% of Python online submissions for Unique Email Addresses.
• Memory Usage: 11.7 MB, less than 92.68% of Python online submissions for Unique Email Addresses.