Pull Request Template

Description

We start by pushing -1 onto the stack.
Every time when we encounter '(' we push.
For every ')' encountered we pop and if the stack is empty we push the current index to the stack
but if the stack is not empty, top subtract index will be the length of the encountered valid string.

Put check marks:

Have you made changes in README file ?

• Added problem & solution under correct topic.
• Specified Space & Time complexity.
• Specified difficulty level, tag & Note(if any).

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Please also note any relevant details for your test configuration.

• Test A
• Test B

Make sure all below guidelines are followed else PR will get Reject:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code so that it is easy to understand
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules