Python · Theory

Tower of Hanoi

Theory

110/268

Tower of Hanoi

Tower of Hanoi is a classic practice problem. State the rule, trace a tiny input, then code. Fibonacci: next = sum of last two. Second largest: watch duplicates. Hanoi: move n-1, biggest, n-1. Distance: sqrt((x2-x1)**2 + (y2-y1)**2).

For Tower of Hanoi — say the output for one small n before you write the loop. That is the exam.

Tower of Hanoi — output — A → B, A → C, B → C. Two disks, three moves.

Exam tip

Rule + one dry-run + then code.

Example

# Tower of Hanoi
def hanoi(n, a, b, c):
    if n == 0:
        return
    hanoi(n - 1, a, c, b)
    print(a, "→", c)
    hanoi(n - 1, b, a, c)
hanoi(2, "A", "B", "C")

Tower of Hanoi — output: A → B, A → C, B → C. Two disks, three moves.

Short notes

DefTower of Hanoi — know the rule.
RuleTower of Hanoi — tiny trace first.
RememberTower of Hanoi — edge cases (n=0, duplicates).

Python · Theory

Tower of Hanoi

← All stacks

Theory

110/268

Tower of Hanoi

For Tower of Hanoi — say the output for one small n before you write the loop. That is the exam.

Tower of Hanoi — output — A → B, A → C, B → C. Two disks, three moves.

Exam tip

Rule + one dry-run + then code.

Example

# Tower of Hanoi
def hanoi(n, a, b, c):
    if n == 0:
        return
    hanoi(n - 1, a, c, b)
    print(a, "→", c)
    hanoi(n - 1, b, a, c)
hanoi(2, "A", "B", "C")

Tower of Hanoi — output: A → B, A → C, B → C. Two disks, three moves.

Short notes

DefTower of Hanoi — know the rule.
RuleTower of Hanoi — tiny trace first.
RememberTower of Hanoi — edge cases (n=0, duplicates).

Tower of Hanoi

Example

Short notes

Questions

Tower of Hanoi

Example

Short notes

Questions