Here are some resources which I refer to for CP, feel free to add anything important
→ Place to find everything related to CP books, blogs, tutorials, platforms and everything you will ever need https://codeforces.com/blog/entry/23054
→ How to decide which type of algorithm will be best for the question depending on the input size (very helpful if you are just starting out)
Overcoming TLE
→ For python coders https://wiki.python.org/moin/PythonSpeed/PerformanceTips
→ Simplified time complexity analysis https://www.hackerearth.com/practice/basic-programming/complexity-analysis/time-and-space-complexity/tutorial/
→ Implementation of any algorithm you will ever come across https://www.geeksforgeeks.org/fundamentals-of-algorithms/
→ Another resource for all programming algorithms https://cp-algorithms.com/