Hi all Codeforces users . i was watching a lecture on greedy algorithm and the lecturer said that you need to read in "Matriods" and "Linear programming " "duality " . ? to get tricks about the greedy choice ?

so can some one explain fast what's these names mean ? and what is the relation between them and greedy ? and i will be thankful if someone gives me a link ? thanks in advance

**#### Hi every Body can some one help me ? why i get TLE in Test 45 ? Theoritically it should pass ? **

HERE

Please i need some help in this problem here why the solution is to sort by S/T ?

int This problem **i am wondering why the greedy algorithm works ? how to prove ,Author said in the tutorial "you need to beleive that it's working " how did he know ? and is it working for any sequence ? i think no ? **

i always have a problem with all greedy problem that is not easy to see its optimal choice ?

some times i get an intuition but i am not sure it works 100% how would i improve my proving skills for greedy .would i try my intuition with code and check if it will get a WA or not ? some tips from you please .

i started reading about Dp bottom up and top down(memoization) . i wonder how could i start easy problems on dp then harder and harder ?

How can i enhance my skills in solving Mathematics and number theory related problems ? my strategy was that pic math problem ..try as much u can then if i couldn't figure a solution . i look at red person and learn how they solve it and read the tutorial ans so on ... that really helped me in learning basic stuff .but this method is so slow ..i need a book or something in math and number theory any tips ?

i need a simple implementation of sorting algorithm in linear time and efficient ? like radix sort or counting sort ? are they really better than merge sort ..if so why people always use nlogn algorithms ?