Probing strategies side by side: linear, quadratic, double hashing

My notes comparing open addressing strategies. h is the hash index, i is the attempt number. Linear: (h + i) mod capacity. Simple, but suffers from primary clustering. Quadratic: (h + i²) mod capacity. Avoids primary clustering but can fail to find an open spot even when one exists. Double hashing: (h + i · h2(key)) mod capacity. Spreads probes out the most, costs a second hash. On removal with open addressing, you can't just empty the slot, or later searches stop too early. Mark it "deleted" instead, and reuse those slots on insert.