Validate Password Strength

Check passwords against length, character variety, and common patterns.

strings validation conditions

Write a function `validate_password(password: str) -> bool` that returns `True` if the password is strong, otherwise `False`.

A password is considered strong if it satisfies **all** of the following rules:
1. **Length**: between 8 and 20 characters inclusive.
2. **Character variety**: contains at least one uppercase letter, one lowercase letter, one digit, and one special character (special characters are any of `!@#$%^&*`).
3. **No whitespace**: does not contain any whitespace characters (space, tab, newline, etc.).
4. **No common pattern**: does not contain the substring `'123'`, `'abc'`, `'password'`, or `'qwerty'` (case-insensitive).

Note: The function should handle empty strings gracefully and should not assume any other characters are special.

Constraints

- `password` is a string of any length (including empty string).
- The function must run in O(n) time where n is the length of the string.

Example

```python
validate_password("StrongP@ss1")   # True
validate_password("weak")           # False (too short)
validate_password("NoSpecial1")     # False (no special char)
validate_password("NoDigit@bc")     # False (no digit)
validate_password("UPPERlower123!") # False (contains '123')
```

10 points ~15 min

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Hints

Use string methods like `.isupper()`, `.islower()`, `.isdigit()` to check character types.

For the special characters, create a set of allowed specials and check membership.

To check whitespace, iterate through characters and use `.isspace()`.

For the common patterns, convert the password to lowercase and check if any of the substrings are present.

Combine all conditions with `and` and return the result.

Test Results

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