Add kotlin code for the chapter of divide and conquer (krahets#1098)

* feat(kotlin):new kotlin support files

* fix(kotlin):

    reviewed the formatting, comments and so on.

* fix(kotlin): fix the indentation and format

* feat(kotlin): Add kotlin code for the backtraking chapter.

* fix(kotlin): fix incorrect output of preorder_traversal_iii_template.kt file

* fix(kotlin): simplify kotlin codes

* fix(kotlin): modify n_queens.kt for consistency.

* feat(kotlin): add kotlin code for computational complexity.

* fix(kotlin): remove iteration folder.

* fix(kotlin): remove n_queens.kt file out of folder.

* fix(kotlin): remove some folders.

* style(kotlin): modified two chapters.

* feat(kotlin): add kotlin code for divide and conquer.

* Update build_tree.kt

* Update hanota.kt

* Delete codes/kotlin/chapter_backtracking directory

* Delete codes/kotlin/chapter_computational_complexity directory

* Delete codes/kotlin/chapter_divide_and_conquer directory

* feat(kotlin): add kotlin code for divide and conquer.

* Update hanota.kt

codes/kotlin/chapter_divide_and_conquer/binary_search_recur.kt

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+/**
+ * File: binary_search_recur.kt
+ * Created Time: 2024-01-25
+ * Author: curtishd ([email protected])
+ */
+
+package chapter_divide_and_conquer.binary_search_recur
+
+/* 二分查找：问题 f(i, j) */
+fun dfs(
+    nums: IntArray,
+    target: Int,
+    i: Int,
+    j: Int
+): Int {
+    // 若区间为空，代表无目标元素，则返回 -1
+    if (i > j) {
+        return -1
+    }
+    // 计算中点索引 m
+    val m = (i + j) / 2
+    return if (nums[m] < target) {
+        // 递归子问题 f(m+1, j)
+        dfs(nums, target, m + 1, j)
+    } else if (nums[m] > target) {
+        // 递归子问题 f(i, m-1)
+        dfs(nums, target, i, m - 1)
+    } else {
+        // 找到目标元素，返回其索引
+        m
+    }
+}
+
+/* 二分查找 */
+fun binarySearch(nums: IntArray, target: Int): Int {
+    val n = nums.size
+    // 求解问题 f(0, n-1)
+    return dfs(nums, target, 0, n - 1)
+}
+
+/* Driver Code */
+fun main() {
+    val target = 6
+    val nums = intArrayOf(1, 3, 6, 8, 12, 15, 23, 26, 31, 35)
+
+    // 二分查找（双闭区间）
+    val index = binarySearch(nums, target)
+    println("目标元素 6 的索引 = $index")
+}

codes/kotlin/chapter_divide_and_conquer/build_tree.kt

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+/**
+ * File: build_tree.kt
+ * Created Time: 2024-01-25
+ * Author: curtishd ([email protected])
+ */
+
+package chapter_divide_and_conquer.build_tree
+
+import utils.TreeNode
+import utils.printTree
+
+/* 构建二叉树：分治 */
+fun dfs(preorder: IntArray, inorderMap: Map<Int?, Int?>, i: Int, l: Int, r: Int): TreeNode? {
+    // 子树区间为空时终止
+    if (r - l < 0) return null
+    // 初始化根节点
+    val root = TreeNode(preorder[i])
+    // 查询 m ，从而划分左右子树
+    val m = inorderMap[preorder[i]]!!
+    // 子问题：构建左子树
+    root.left = dfs(preorder, inorderMap, i + 1, l, m - 1)
+    // 子问题：构建右子树
+    root.right = dfs(preorder, inorderMap, i + 1 + m - l, m + 1, r)
+    // 返回根节点
+    return root
+}
+
+/* 构建二叉树 */
+fun buildTree(preorder: IntArray, inorder: IntArray): TreeNode? {
+    // 初始化哈希表，存储 inorder 元素到索引的映射
+    val inorderMap: MutableMap<Int?, Int?> = HashMap()
+    for (i in inorder.indices) {
+        inorderMap[inorder[i]] = i
+    }
+    val root = dfs(preorder, inorderMap, 0, 0, inorder.size - 1)
+    return root
+}
+
+/* Driver Code */
+fun main() {
+    val preorder = intArrayOf(3, 9, 2, 1, 7)
+    val inorder = intArrayOf(9, 3, 1, 2, 7)
+    println("前序遍历 = " + preorder.contentToString())
+    println("中序遍历 = " + inorder.contentToString())
+
+    val root = buildTree(preorder, inorder)
+    println("构建的二叉树为：")
+    printTree(root)
+}

codes/kotlin/chapter_divide_and_conquer/hanota.kt

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+/**
+ * File: hanota.kt
+ * Created Time: 2024-1-25
+ * Author: curtishd ([email protected])
+ */
+
+package chapter_divide_and_conquer.hanota
+
+/* 移动一个圆盘 */
+fun move(src: MutableList<Int>, tar: MutableList<Int>) {
+    // 从 src 顶部拿出一个圆盘
+    val pan: Int = src.removeAt(src.size - 1)
+    // 将圆盘放入 tar 顶部
+    tar.add(pan)
+}
+
+/* 求解汉诺塔问题 f(i) */
+fun dfs(i: Int, src: MutableList<Int>, buf: MutableList<Int>, tar: MutableList<Int>) {
+    // 若 src 只剩下一个圆盘，则直接将其移到 tar
+    if (i == 1) {
+        move(src, tar)
+        return
+    }
+    // 子问题 f(i-1) ：将 src 顶部 i-1 个圆盘借助 tar 移到 buf
+    dfs(i - 1, src, tar, buf)
+    // 子问题 f(1) ：将 src 剩余一个圆盘移到 tar
+    move(src, tar)
+    // 子问题 f(i-1) ：将 buf 顶部 i-1 个圆盘借助 src 移到 tar
+    dfs(i - 1, buf, src, tar)
+}
+
+/* 求解汉诺塔问题 */
+fun solveHanota(A: MutableList<Int>, B: MutableList<Int>, C: MutableList<Int>) {
+    val n = A.size
+    // 将 A 顶部 n 个圆盘借助 B 移到 C
+    dfs(n, A, B, C)
+}
+
+/* Driver Code */
+fun main() {
+    // 列表尾部是柱子顶部
+    val A: MutableList<Int> = ArrayList(mutableListOf(5, 4, 3, 2, 1))
+    val B: MutableList<Int> = ArrayList()
+    val C: MutableList<Int> = ArrayList()
+    println("初始状态下：")
+    println("A = $A")
+    println("B = $B")
+    println("C = $C")
+
+    solveHanota(A, B, C)
+
+    println("圆盘移动完成后：")
+    println("A = $A")
+    println("B = $B")
+    println("C = $C")
+}