Hello, I have been coding last three years. I have solved quite a number of problems in various sites like uva, lightoj.I also completed static a2oj(<1300) rating problems. But still in the codeforces contest there are so many problems I faced lately. Like, I solved A no question after 30-40 min. Someday I can't get the efficient algorithm to solve B no question. In some contest, I get wa for some very silly mistakes like not using long long integer or like not checking critical test cases etc. Here so many of the great coders just take 1 or 2 years to become blue or even further .But I don't know what I am missing in my approaches?