build

docs/chapter_divide_and_conquer/build_binary_tree_problem.md

@@ -449,7 +449,13 @@ comments: true
 
     ```kotlin title="build_tree.kt"
     /* 构建二叉树：分治 */
-    fun dfs(preorder: IntArray, inorderMap: Map<Int?, Int?>, i: Int, l: Int, r: Int): TreeNode? {
+    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
@@ -467,7 +473,7 @@ comments: true
     /* 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()
+        val inorderMap = HashMap<Int?, Int?>()
         for (i in inorder.indices) {
             inorderMap[inorder[i]] = i
         }