hello-algo/en/codes/javascript/chapter_divide_and_conquer/hanota.js

53 lines
1.4 KiB
JavaScript

/**
* File: hanota.js
* Created Time: 2023-07-30
* Author: yuan0221 (yl1452491917@gmail.com)
*/
/* Move a disc */
function move(src, tar) {
// Take out a disc from the top of src
const pan = src.pop();
// Place the disc on top of tar
tar.push(pan);
}
/* Solve the Tower of Hanoi problem f(i) */
function dfs(i, src, buf, tar) {
// If only one disc remains on src, move it to tar
if (i === 1) {
move(src, tar);
return;
}
// Subproblem f(i-1): move the top i-1 discs from src with the help of tar to buf
dfs(i - 1, src, tar, buf);
// Subproblem f(1): move the remaining one disc from src to tar
move(src, tar);
// Subproblem f(i-1): move the top i-1 discs from buf with the help of src to tar
dfs(i - 1, buf, src, tar);
}
/* Solve the Tower of Hanoi problem */
function solveHanota(A, B, C) {
const n = A.length;
// Move the top n discs from A with the help of B to C
dfs(n, A, B, C);
}
/* Driver Code */
// The tail of the list is the top of the pillar
const A = [5, 4, 3, 2, 1];
const B = [];
const C = [];
console.log('Initial state:');
console.log(`A = ${JSON.stringify(A)}`);
console.log(`B = ${JSON.stringify(B)}`);
console.log(`C = ${JSON.stringify(C)}`);
solveHanota(A, B, C);
console.log('After the discs are moved:');
console.log(`A = ${JSON.stringify(A)}`);
console.log(`B = ${JSON.stringify(B)}`);
console.log(`C = ${JSON.stringify(C)}`);