I am confused ,which path should I follow out of these :-
should I practise question based on algorithms like I should search for particular type of algorithm and do lots of question of it after learning the algorithm from :-https://codeforces.me/problemset or https://cp-algorithms.com/ .
should I practise question based on difficulty from :- https://www.a2oj.com/Ladders.html and learn algorithm which come on my way of solving question .
I loved the first way but the problem is there are lot of algorithms and in which sequence should I learn them I don't know .please help.
In my opinion, you should combine these approaches like 70-75% of practicing problems and the remaining 25-30% of learning algorithms because if you can't solve well, you won't be able to use these algorithms.
What do you do even if you know the basic algorithms but cannot apply them?
Than you should solve lots of problems and see editorials to see what kind of problems can be solved by which algorithms.
In my opinion you should follow upsolving.Lets take an example,in a contest you have solved three problems.then after completion of contest you should try 4th one.If you are not able to solve then see the tutorial.if you find something new then study and practice.Don't touch too much hard problem.It will be really helpful
Start with "Do a lot of..." then append any type of practice.
Try to push your level. If you are able to solve problems of difficulty rating 1400 then try to solve 1600-1700 difficulty rated problems on codeforces. If you are not able to solve it then look the editorials for hint and learn something new. Suppose in the editorial they used term which you don't know then google it and solve some problems on that topic to have the basics clear (for example, in the editorial the term "trie" is written and you don't know about its implementation and applications, then search it in google else you can go to hackerearth or hackerrank website and practice the basics from there). Also after giving a contest try to solve atleast one problem which you could not solve during the contests.