feat(kotlin): Add kotlin code for backtracking chapter (#1088)

* 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.

codes/kotlin/chapter_backtracking/permutations_ii/permutations_ii.kt

@@ -0,0 +1,55 @@
+/**
+ * File: permutations_ii.kt
+ * Created Time: 2024-01-25
+ * Author: curtishd (1023632660@qq.com)
+ */
+
+package chapter_backtracking.permutations_ii
+
+/* 回溯算法：全排列 II */
+fun backtrack(
+    state: MutableList<Int>,
+    choices: IntArray,
+    selected: BooleanArray,
+    res: MutableList<MutableList<Int>?>
+) {
+    // 当状态长度等于元素数量时，记录解
+    if (state.size == choices.size) {
+        res.add(ArrayList(state))
+        return
+    }
+    // 遍历所有选择
+    val duplicated: MutableSet<Int> = HashSet()
+    for (i in choices.indices) {
+        val choice = choices[i]
+        // 剪枝：不允许重复选择元素 且 不允许重复选择相等元素
+        if (!selected[i] && !duplicated.contains(choice)) {
+            // 尝试：做出选择，更新状态
+            duplicated.add(choice) // 记录选择过的元素值
+            selected[i] = true
+            state.add(choice)
+            // 进行下一轮选择
+            backtrack(state, choices, selected, res)
+            // 回退：撤销选择，恢复到之前的状态
+            selected[i] = false
+            state.removeAt(state.size - 1)
+        }
+    }
+}
+
+/* 全排列 II */
+fun permutationsII(nums: IntArray): MutableList<MutableList<Int>?> {
+    val res: MutableList<MutableList<Int>?> = ArrayList()
+    backtrack(ArrayList(), nums, BooleanArray(nums.size), res)
+    return res
+}
+
+/* Driver Code */
+fun main() {
+    val nums = intArrayOf(1, 2, 2)
+
+    val res = permutationsII(nums)
+
+    println("输入数组 nums = ${nums.contentToString()}")
+    println("所有排列 res = $res")
+}