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Strong Password Checker

Certification: Advanced Level Accuracy: 0% Submissions: 0 Points: 15

Write a C program to check if a password is strong and return the minimum number of steps required to make it strong. A password is considered strong if it satisfies ALL of the following criteria:

    
            
  • It has at least 6 characters and at most 20 characters.
    • 
            
  • It contains at least one lowercase letter, at least one uppercase letter, and at least one digit.
    • 
            
  • It does not contain three repeating characters in a row (i.e., "...aaa..." is weak, but "...aa...a..." is strong, assuming other conditions are met).
    •

You can perform the following operations: Insert a character to any position, Delete a character from any position, Replace a character at any position.

Example 1
    
            
  • Input: password = "a"
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  • Output: 5
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  • Explanation: 
    • Password length is 1, needs at least 6 characters. 
    • Missing uppercase letter and digit. 
    • Need to add 5 characters to reach minimum length while satisfying missing type requirements.
    •
Example 2
    
            
  • Input: password = "aaaaaaaaaaaaaaaaaaaaa"
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  • Output: 7
    • 
            
  • Explanation: 
    • Password length is 21, exceeds maximum of 20. 
    • Has lowercase but missing uppercase and digit. 
    • Has repeating characters "aaa" multiple times. 
    • Need to delete 1 character and replace others to fix issues.
    •
Constraints
    
            
  • 1 ≤ password.length ≤ 50
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  • password consists of only English letters and digits
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  • You can perform insert, delete, or replace operations
    • 
            
  • Time Complexity: O(n) where n is password length
    • 
            
  • Space Complexity: O(1)
    •
StringsDeloitteLTIMindtree
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Hint
Solution

Solution Hints

    
            
  • Check the length first - if too short, calculate additions needed
    • 
            
  • If too long, calculate deletions needed and prioritize fixing repeating sequences
    • 
            
  • Count missing character types (lowercase, uppercase, digit)
    • 
            
  • Handle repeating sequences by counting groups of 3+ consecutive characters
    • 
            
  • For short passwords, additions can fix both length and missing types
    • 
            
  • For long passwords, deletions and replacements should be optimized
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  • Use greedy approach to minimize total operations
    •

Steps to solve by this approach:

 Step 1: Calculate password length and check if it's too short (< 6), good (6-20), or too long (> 20)

 Step 2: Iterate through password to identify missing character types (lowercase, uppercase, digit)

 Step 3: Count repeating character sequences of 3 or more consecutive identical characters

 Step 4: For short passwords, calculate additions needed and check if they can satisfy missing types

 Step 5: For good length passwords, return maximum of repeating sequences and missing types

 Step 6: For long passwords, calculate deletions needed and adjust repeating sequences accordingly

 Step 7: Return minimum total operations considering all constraints and optimization strategies

Submitted Code :