Pattern 03 of 08 · fast-slow-pointers

Fast & Slow Pointers

Traverse linear structures (linked lists, sequence graphs) at two distinct speeds to detect cycles and identify midpoint boundaries.

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Pattern InvariantFast & Slow Pointers

Floyd's Cycle Finding Algorithm (Tortoise & Hare)

Step 1 of 5

Slow/Fast

Node 0

Node 1

Node 2 (Cycle Start)

Node 3

Node 4

Node 5

[Node 2]

Initial state: Both Slow (the tortoise) and Fast (the hare) start at head Node 0 (A).

Speed:

3 problems