How to validate GUID (Globally Unique Identifier) using Regular Expression

Given string str, the task is to check whether the given string is a valid GUID (Globally Unique Identifier) or not by using Regular Expression.
The valid GUID (Globally Unique Identifier) must specify the following conditions: 

1. It should be a 128-bit number.
2. It should be 36 characters (32 hexadecimal characters and 4 hyphens) long.
3. It should be displayed in five groups separated by hyphens (-).
4. Microsoft GUIDs are sometimes represented with surrounding braces.

Examples: 

Input: str = "123e4567-e89b-12d3-a456-9AC7CBDCEE52" 
Output: true 
Explanation: 
The given string satisfies all the above mentioned conditions. Therefore, it is a valid GUID (Globally Unique Identifier).
Input: str = "123e4567-h89b-12d3-a456-9AC7CBDCEE52" 
Output: false 
Explanation: 
The given string contains 'h', the valid hexadecimal characters should be followed by character from a-f, A-F, and 0-9. Therefore, it is not a valid GUID (Globally Unique Identifier).
Input: str = "123e4567-h89b-12d3-a456" 
Output: false 
Explanation: 
The given string has 20 characters. Therefore, it is not a valid GUID (Globally Unique Identifier). 

Approach: The idea is to use Regular Expression to solve this problem. The following steps can be followed to compute the answer:

• Get the String.
• Create a regular expression to check valid GUID (Globally Unique Identifier) as mentioned below:
   

regex = "^[{]?[0-9a-fA-F]{8}-([0-9a-fA-F]{4}-){3}[0-9a-fA-F]{12}[}]?$" 

• Where: 
  
  • ^ represents the starting of the string.
  • [{]? represents the '{' character that is optional.
  • [0-9a-fA-F]{8} represents the 8 characters from a-f, A-F, and 0-9.
  • - represents the hyphens.
  • ([0-9a-fA-F]{4}-){3} represents the 4 characters from a-f, A-F, and 0-9 that is repeated 3 times separated by a hyphen (-).
  • [0-9a-fA-F]{12} represents the 12 characters from a-f, A-F, and 0-9.
  • [}]? represents the '}' character that is optional.
  • $ represents the ending of the string.
• Match the given string with the Regular Expression. In Java, this can be done by using Pattern.matcher().
• Return true if the string matches with the given regular expression, else return false.

Below is the implementation of the above approach:
 

true
true
false
false

Time Complexity: O(N) for each test case, where N is the length of the given string. 
Auxiliary Space: O(1)