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

Author: everthis

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

@@ -65,3 +65,76 @@ function helper(node, res) {
  * var param_3 = obj.hasPrev()
  * var param_4 = obj.prev()
  */
+
+// another
+
+/**
+ * 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.nums = []
+  this.stack = []
+  this.node = root
+  this.i = 0 // pointer to next node
+  this.size = 0
+}
+
+/**
+ * @return {boolean}
+ */
+BSTIterator.prototype.hasNext = function () {
+  return this.i < this.size || this.stack.length > 0 || !!this.node
+}
+
+/**
+ * @return {number}
+ */
+BSTIterator.prototype.next = function () {
+  if (this.i < this.size) return this.nums[this.i++]
+  if (this.stack.length || this.node) {
+    while (this.node) {
+      this.stack.push(this.node)
+      this.node = this.node.left
+    }
+    this.node = this.stack.pop()
+    this.i += 1
+    this.size += 1
+    const val = this.node.val
+    this.nums.push(val)
+    this.node = this.node.right
+    return val
+  }
+  return -1
+}
+
+/**
+ * @return {boolean}
+ */
+BSTIterator.prototype.hasPrev = function () {
+  return this.i - 2 >= 0
+}
+
+/**
+ * @return {number}
+ */
+BSTIterator.prototype.prev = function () {
+  return this.nums[--this.i - 1]
+}
+
+/**
+ * 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()
+ */
+