InterviewBit Problems   Longest valid Parentheses : Solved

About the Longest valid Parentheses : Solved category (1)
O(n) solution with two pointers (1)
No need of DP. Simple stack based solution (1)
C++ sol using Stack and DP (1)
An O(n) time O(1) space using two pointers(close and open) (2)
Solution fails a test case (2)
C++ solution using stacks with explanation (1)
An O(n) time Solution using stack (1)
C++ solution with explaination (1)
O(n) by using stack to store the indexes that disrupt the validness (1)
Very very simple O(1) space and O[n) time complexity without DP (1)
An easy approach to this solution no need of DP (2)
Solution with O(1) space complexity and O(n) time complexity (1)
1 stack, O(n) solution without DP (3)
Completely different approach without DP..very easy (1)
What's wrong with this code? Please suggest changes (1)
No sure why this didn't work. Any tips on this one? (1)
Whats wrong with this approach? Any pointers? (1)
2 stacks, O(n) solution without DP (1)
Same code is working in python2.7 but gives seg. fault error in python3 . Can somebody tell why it is so? (1)
Longest_valid_Parentheses-DP_solution_in_O(n) (1)
This is very bad... same code gets accepted in c but not in c++... and it gives W (3)