The Tower of Hanoi problem is a classic example of a problem that can be…
2025
The Tower of Hanoi problem is a classic example of a problem that can be solved using recursion. How many minimum moves are required to solve the Tower of Hanoi problem with 3 disks?
Answer: B. 7 — ConceptThe Tower of Hanoi puzzle has a well-known recurrence for the minimum number of moves: T(n) = 2·T(n-1) + 1, with base case T(1) = 1. Solving this…
- A.
3
- B.
7
- C.
15
- D.
63
Attempted by 4 students.
Show answer & explanation
Correct answer: B
Concept
The Tower of Hanoi puzzle has a well-known recurrence for the minimum number of moves: T(n) = 2·T(n-1) + 1, with base case T(1) = 1. Solving this recurrence gives the closed-form formula: Moves = 2n − 1, where n is the number of disks.
Application
Identify the number of disks: n = 3.
Write the closed-form formula: Moves = 2n − 1.
Substitute n = 3: Moves = 23 − 1.
Evaluate the power: 23 = 8.
Subtract: 8 − 1 = 7.
Cross-check
Verify independently using the recurrence itself, building up from the base case: T(1) = 1. T(2) = 2·T(1) + 1 = 2·1 + 1 = 3. T(3) = 2·T(2) + 1 = 2·3 + 1 = 7. This matches the closed-form result exactly.
Result
Therefore, the minimum number of moves required to solve the Tower of Hanoi problem with 3 disks is 7.
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