can anyone help me with knapsack 0/1 dp problemset or any other resource? or you can just comment the problem you think would be good for learning knapsack dp. i am not able to solve advanced problems in knapsack dp. thanks!!

https://codeforces.com/problemset/problem/1063/B this question can be done with djikstra as well. but dont know y its giving TLE. https://ideone.com/Az9ZAL (its properly commented -running and no templates are used so wont be tough to read) .using djikstra i am assigning 1 unit weight to all the left edges. if anyone can suggest any optimization i would be very thankful. UPD-error found i was putting less than -equal sign for checking djikstra

https://ideone.com/yQshPe this is my submission i cant figure why its always showing TLE. https://codingcompetitions.withgoogle.com/codejam/round/00000000000516b9/0000000000134e91#

I have been continously participating in contests for an year. I have been upsolving questions from contests too.Still I havent reached the level of solving D,E during contest(always due to some small problem) So now i want to ask what should be the way further to practise questions? 1. I have previously read practisiong tough questions is more important(We get ample practise of easy to moderate questions through contests). So how to filter questions?. The thing is if we select a very tough question then it's out of scope and we dont learn anything new and if we select too easy still we dont learn anything new? 2. Is codeforces the best website for practise or are there other websites with very good editorials,codes,filters etc. for practise? Thanks!!