56 lines
1.5 KiB
Kotlin
56 lines
1.5 KiB
Kotlin
/**
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* File: hanota.kt
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* Created Time: 2024-01-25
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* Author: curtishd (1023632660@qq.com)
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*/
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package chapter_divide_and_conquer.hanota
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/* Move a disc */
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fun move(src: MutableList<Int>, tar: MutableList<Int>) {
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// Take out a disc from the top of src
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val pan = src.removeAt(src.size - 1)
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// Place the disc on top of tar
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tar.add(pan)
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}
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/* Solve the Tower of Hanoi problem f(i) */
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fun dfs(i: Int, src: MutableList<Int>, buf: MutableList<Int>, tar: MutableList<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, 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 - 1, src, tar, buf)
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// Subproblem f(1): move the remaining one disc from src to tar
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move(src, 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 - 1, buf, src, tar)
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}
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/* Solve the Tower of Hanoi problem */
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fun solveHanota(A: MutableList<Int>, B: MutableList<Int>, C: MutableList<Int>) {
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val n = A.size
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// Move the top n discs from A with the help of B to C
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dfs(n, A, B, C)
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}
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/* Driver Code */
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fun main() {
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// The tail of the list is the top of the pillar
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val A = mutableListOf(5, 4, 3, 2, 1)
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val B = mutableListOf<Int>()
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val C = mutableListOf<Int>()
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println("Initial state:")
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println("A = $A")
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println("B = $B")
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println("C = $C")
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solveHanota(A, B, C)
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println("After the discs are moved:")
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println("A = $A")
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println("B = $B")
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println("C = $C")
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} |