Linked List Cycle II - Walkthrough

List: $3 \to 2 \to 0 \to -4 \to 2$ (cycle at node $2$). The last node points back to the second node, creating a loop. Phase $1$: slow and fast start at $3$. After $3$ steps, they meet at node $-4$ (inside the cycle). Slow traveled $3$ steps, fast traveled $6$ steps.

They met inside the cycle. Phase $2$: slow resets to $3$, fast stays at $-4$. Both move one step at a time. They meet at node $2$, the cycle start. Return node $2$. This is where the tail ends and the cycle begins.