Detecting a cycle L Detecting a cycle L

Detecting a cycle L

Detecting a cycle L p

Detecting a cycle L p stack

Detecting a cycle L p stack

Detecting a cycle L p

Detecting a cycle p Cycle detected at p L

Now restore the list using the saved pointers p L

Restoring. . . L p

Restoring. . . L p

Restoring. . . L p

Restoring. . . L p

Restored! L

How much time and space? L

How much time and space? p O(N) time L O(N) space for stack

Detecting a cycle with two-speed pointers L p q

Detecting a cycle with two-speed pointers L q p

Detecting a cycle with two-speed pointers L q p

Detecting a cycle with two-speed pointers L q p

Detecting a cycle with two-speed pointers L q p

Detecting a cycle with two-speed pointers p L q

Detecting a cycle with two-speed pointers p L q

Detecting a cycle with two-speed pointers L p q

Detecting a cycle with two-speed pointers L q p

Detecting a cycle with two-speed pointers L Cycle detected p q

How much time and space? L

Two-speed method: a larger example

Two-speed method: a larger example

Two-speed method: a larger example

Two-speed method: a larger example

Two-speed method: a larger example

Two-speed method: a larger example

Two-speed method: a larger example

Two-speed method: a larger example

Two-speed method: a larger example

Two-speed method: a larger example

Two-speed method: a larger example

Two-speed method: a larger example

Two-speed method: a larger example

Two-speed method: a larger example

Two-speed method: a larger example

Two-speed method: a larger example

Two-speed method: a larger example

Two-speed method: a larger example

Two-speed method: a larger example

Two-speed method: a larger example

Two-speed method: a larger example Cycle detected!

How much time and space?

How much time and space? O(N) time O(1) space