Create 1586-binary-search-tree-iterator-ii.js

Author: everthis

1586-binary-search-tree-iterator-ii.js

@@ -0,0 +1,67 @@
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ */
+const BSTIterator = function(root) {
+  this.r = root
+  const ans = []
+  helper(root, ans)
+  this.arr = ans
+  this.cur = -1
+};
+
+/**
+ * @return {boolean}
+ */
+BSTIterator.prototype.hasNext = function() {
+  return this.arr.length && this.cur < this.arr.length - 1
+};
+
+/**
+ * @return {number}
+ */
+BSTIterator.prototype.next = function() {
+  this.cur += 1
+  return this.arr[this.cur]
+};
+
+/**
+ * @return {boolean}
+ */
+BSTIterator.prototype.hasPrev = function() {
+  return this.arr.length && this.cur > 0
+};
+
+/**
+ * @return {number}
+ */
+BSTIterator.prototype.prev = function() {
+  return this.arr[--this.cur]
+};
+
+function helper(node, res) {
+  if(node == null) return
+  if(node.left) {
+    helper(node.left, res)
+  }
+  res.push(node.val)
+  if(node.right) {
+    helper(node.right, res)
+  }
+}
+
+/** 
+ * Your BSTIterator object will be instantiated and called as such:
+ * var obj = new BSTIterator(root)
+ * var param_1 = obj.hasNext()
+ * var param_2 = obj.next()
+ * var param_3 = obj.hasPrev()
+ * var param_4 = obj.prev()
+ */