Big-O Cheat Sheet: Costs, Traps And The Doubling Test

Big-O explained without any maths, using one question — when the input doubles, what happens to the work? Inside: a real time-to-run table for n = 10, 1,000 and 1,000,000, what the constraint line in a coding test is telling you, the average and worst cost of every structure a fresher uses with a one-line "pick this when", the sort your language actually runs, five nested loops read line by line, space complexity and the recursion-stack trap, and the six traps that turn a correct answer into Time Limit Exceeded — each with the fix and a measured before-and-after. 14 pages, PDF.