Greedy Algorithms and the Greedy Choice

Greedy algorithms are the shortest solutions and the easiest to get wrong. The code is often a sort followed by a single loop; the difficulty is entirely in justifying that taking the locally best option gives a globally optimal answer, which for many problems it does not.

Each lesson pairs the algorithm with the argument for why its greedy choice is safe. Interval problems get particular attention because they are the most common greedy family in interviews, and because the correct sort key — by end time, not start time — is exactly the sort of decision a visualizer makes obvious and a paragraph does not.