Update 105-construct-binary-tree-from-preorder-and-inorder-traversal.js

Author: everthis

105-construct-binary-tree-from-preorder-and-inorder-traversal.js

@@ -1,3 +1,36 @@
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val) {
+ *     this.val = val;
+ *     this.left = this.right = null;
+ * }
+ */
+/**
+ * @param {number[]} preorder
+ * @param {number[]} inorder
+ * @return {TreeNode}
+ */
+const buildTree = function(preorder, inorder) {
+  if(preorder.length === 0 && inorder.length === 0) return null
+  const val = preorder[0]
+  const node = new TreeNode(val)
+  const inIdx = inorder.indexOf(val)
+  const leftIn = inorder.slice(0, inIdx)
+  const rightIn = inorder.slice(inIdx + 1)
+  
+  const leftPre = preorder.slice(1, leftIn.length + 1)
+  const rightPre = preorder.slice(leftIn.length + 1)
+  
+  // console.log(leftIn, rightIn, leftPre, rightPre)
+  node.left = buildTree(leftPre, leftIn)
+  node.right = buildTree(rightPre, rightIn)
+  return node
+};
+
+
+// another
+
+
 /**
  * Definition for a binary tree node.
  * function TreeNode(val) {