Greedy

A greedy algorithm builds a solution by always taking whatever looks best right now and never reconsidering. For scheduling the most meetings in one room, always picking the meeting that ends earliest happens to give the best possible answer. But greedy is only correct for problems with the right structure, and it fails quietly when it isn’t: making change for 6 with coins of 1, 3 and 4, grabbing the 4 first leads to three coins when two 3s would do. So the real skill is proving it works, usually with an exchange argument showing that swapping any optimal solution’s choice for the greedy one never makes things worse. When it does work, it’s usually fast and simple.