Bit Manipulation Mastery

Nobody derives n & (n-1) at the whiteboard under pressure. You've either seen the trick or you haven't, and staring harder won't get you there. The saving grace is that the whole inventory is small enough to hold in your head, and once you have it the problems collapse. This lesson runs from the core operations through bitmask DP, with the worked examples and complexity analysis that turn a partial answer into a full one.