8.0K
NEValid Parentheses 🔥 The Stack Trick Every Coding Interview Uses
This is one of the most asked coding interview questions.
Given a string containing (), {}, [], you must determine if the parentheses are valid and correctly ordered.
The trick interviewers expect is using a Stack.
✔ Push opening brackets
✔ When you see a closing bracket, check the top of the stack
✔ If it matches → pop it
✔ If not → invalid
If the stack is empty at the end → the string is valid.
⏱ Time Complexity: O(n)
📦 Space Complexity: O(n)
This problem teaches a fundamental stack pattern used in many coding interviews.
📌 Save this reel for your DSA preparation
💬 Comment “STACK” if you want more stack interview problems.
#leetcode
#datastructures
#codinginterview
#algorithms
#python
@next.tech12
![#Valid Parentheses Reel by @codewithupasana - LeetCode 20: Valid Parentheses
You're given a string of brackets - (), {}, []
Your job? Check if it's valid, meaning:
✅ Every opening has a closing
✅](https://image.pictame.com/img/514041031_17914065933140444_3026080617525550810_n.jpg?hash=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)
![#Valid Parentheses Reel by @rakeshcodeburner (verified account) - Valid Parentheses - Stack Pattern (LeetCode 20)
Given a string containing (), {}, and [], check if the parentheses are valid.
📌 Key idea:
Push ope](https://image.pictame.com/img/641978580_17876404461520753_4815923042189862026_n.jpg?hash=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)
![#Valid Parentheses Reel by @bytesizeddev - 20. Valid Parentheses
Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.
Solut](https://image.pictame.com/img/498158675_662316229905420_4906555074293463686_n.jpg?hash=aHR0cHM6Ly9zY29udGVudC1mcmEzLTEuY2RuaW5zdGFncmFtLmNvbS92L3Q1MS43MTg3OC0xNS80OTgxNTg2NzVfNjYyMzE2MjI5OTA1NDIwXzQ5MDY1NTUwNzQyOTM0NjM2ODZfbi5qcGc/c3RwPWRzdC1qcGdfZTM1X3M2NDB4NjQwX3R0NiZfbmNfY2F0PTEwNSZjY2I9Ny01Jl9uY19zaWQ9MThkZTc0JmVmZz1leUpsWm1kZmRHRm5Jam9pUTB4SlVGTXVZbVZ6ZEY5cGJXRm5aVjkxY214blpXNHVRek1pZlElM0QlM0QmX25jX29oYz1fNlp3MU5zSkRwNFE3a052d0U1LU80aCZfbmNfb2M9QWRyc2JpZ2xqaWItYk9HbF9iRFJqWFRQZHJ1aTY0MnhEZTJvdDRldVNNNWZvdmxvTndOSUd0QWNINjNWWjNUdndGNCZfbmNfenQ9MjMmX25jX2h0PXNjb250ZW50LWZyYTMtMS5jZG5pbnN0YWdyYW0uY29tJl9uY19naWQ9VF9kSFlLb0JGdmdJckQxdGozOUNGdyZfbmNfc3M9N2EzMGYmb2g9MDBfQWZ4dUJZQUdGWXhORkxQNnk2bVhPN0JnX1VuOVVyZVlPbG11OEMtLXNBZnExQSZvZT02OUNFNzNFNA==)
![#Valid Parentheses Reel by @itssiddharthsinghh - Day 88/100: Today I solved 4 questions based on strings:
1) Buddy Strings [easy]
2) Additive Number [medium]
3) Top K Frequent Words [medium]
4) Minim](https://image.pictame.com/img/503291249_3590433787758656_3188990337696516103_n.jpg?hash=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)