59 lines
1.6 KiB
Swift
59 lines
1.6 KiB
Swift
/**
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* File: hanota.swift
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* Created Time: 2023-09-02
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* Author: nuomi1 (nuomi1@qq.com)
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*/
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/* Move a disc */
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func move(src: inout [Int], tar: inout [Int]) {
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// Take out a disc from the top of src
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let pan = src.popLast()!
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// Place the disc on top of tar
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tar.append(pan)
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}
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/* Solve the Tower of Hanoi problem f(i) */
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func dfs(i: Int, src: inout [Int], buf: inout [Int], tar: inout [Int]) {
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// If only one disc remains on src, move it to tar
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if i == 1 {
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move(src: &src, tar: &tar)
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return
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}
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// Subproblem f(i-1): move the top i-1 discs from src with the help of tar to buf
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dfs(i: i - 1, src: &src, buf: &tar, tar: &buf)
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// Subproblem f(1): move the remaining one disc from src to tar
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move(src: &src, tar: &tar)
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// Subproblem f(i-1): move the top i-1 discs from buf with the help of src to tar
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dfs(i: i - 1, src: &buf, buf: &src, tar: &tar)
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}
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/* Solve the Tower of Hanoi problem */
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func solveHanota(A: inout [Int], B: inout [Int], C: inout [Int]) {
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let n = A.count
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// The tail of the list is the top of the pillar
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// Move the top n disks from src with the help of B to C
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dfs(i: n, src: &A, buf: &B, tar: &C)
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}
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@main
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enum Hanota {
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/* Driver Code */
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static func main() {
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// The tail of the list is the top of the pillar
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var A = [5, 4, 3, 2, 1]
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var B: [Int] = []
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var C: [Int] = []
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print("Initial state:")
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print("A = \(A)")
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print("B = \(B)")
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print("C = \(C)")
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solveHanota(A: &A, B: &B, C: &C)
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print("After the discs are moved:")
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print("A = \(A)")
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print("B = \(B)")
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print("C = \(C)")
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}
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}
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