tool · interactive solver · classic algorithm · recursion visualized

Tower of Hanoi

Interactive Tower of Hanoi visualizer. Pick the number N of disks, press play and watch the recursive algorithm move them one at a time. Every operation is logged below. The optimal solution takes 2^n − 1 moves.

moves(n) = 2ⁿ − 1

hanoi::solver — floriano@neural-link idle

disks (n) 4 speed 320ms

move 00 / 15

progress

last op —

tail -f /hanoi/operations.log 0 ops

The algorithm, in three lines

The classic Tower of Hanoi solution is recursive: to move n disks from A to C using B as a buffer, first move the n−1 subset onto B, then the largest disk onto C, then the subset from B to C.

function hanoi(n, from, via, to):
    if n == 0: return
    hanoi(n - 1, from, to, via)   // 1. move top n-1 disks from FROM to VIA
    move disk n: from → to        // 2. move the largest free disk to TO
    hanoi(n - 1, via, from, to)   // 3. move n-1 disks from VIA to TO

The minimum number of moves grows exponentially. n = 10 needs 1023 operations. n = 20 needs more than a million.