Strong Password Checker II

Problem Description

A password is said to be strong if it satisfies all the following criteria:

• It has at least 8 characters.
• It contains at least one lowercase letter.
• It contains at least one uppercase letter.
• It contains at least one digit.
• It contains at least one special character from the set "!@#$%^&*()-+".
• It does not contain 2 of the same character in adjacent positions.

Given a string password, return true if it is a strong password. Otherwise, return false.

Key Insights

• Ensure the password length is at least 8 characters.
• Check for the presence of at least one lowercase letter, one uppercase letter, one digit, and one special character.
• Verify that no two adjacent characters are the same.
• Utilize a single pass through the string to check all these conditions to maintain efficiency.

Space and Time Complexity

Time Complexity: O(n), where n is the length of the password. Space Complexity: O(1), as we use a fixed number of variables for checking conditions.

Solution

To determine if a password is strong, we can use a single traversal approach. We will iterate through each character of the password while checking for the required conditions:

1. Count the number of characters to ensure the length is at least 8.
2. Use boolean flags to track the presence of lowercase, uppercase, digit, and special characters.
3. Check for adjacent duplicate characters during the iteration. If all conditions are met, we return true; otherwise, we return false.

Code Solutions