Add solution #510

Author: JoshCrozier

README.md

@@ -498,6 +498,7 @@
 507|[Perfect Number](./solutions/0507-perfect-number.js)|Easy|
 508|[Most Frequent Subtree Sum](./solutions/0508-most-frequent-subtree-sum.js)|Medium|
 509|[Fibonacci Number](./solutions/0509-fibonacci-number.js)|Easy|
+510|[Inorder Successor in BST II](./solutions/0510-inorder-successor-in-bst-ii.js)|Medium|
 513|[Find Bottom Left Tree Value](./solutions/0513-find-bottom-left-tree-value.js)|Medium|
 514|[Freedom Trail](./solutions/0514-freedom-trail.js)|Hard|
 515|[Find Largest Value in Each Tree Row](./solutions/0515-find-largest-value-in-each-tree-row.js)|Medium|

solutions/0510-inorder-successor-in-bst-ii.js

@@ -0,0 +1,50 @@
+/**
+ * 510. Inorder Successor in BST II
+ * https://leetcode.com/problems/inorder-successor-in-bst-ii/
+ * Difficulty: Medium
+ *
+ * Given a node in a binary search tree, return the in-order successor of that node in the BST.
+ * If that node has no in-order successor, return null.
+ *
+ * The successor of a node is the node with the smallest key greater than node.val.
+ *
+ * You will have direct access to the node but not to the root of the tree. Each node will have
+ * a reference to its parent node. Below is the definition for Node:
+ *
+ * class Node {
+ *     public int val;
+ *     public Node left;
+ *     public Node right;
+ *     public Node parent;
+ * }
+ */
+
+/**
+ * // Definition for a _Node.
+ * function _Node(val) {
+ *    this.val = val;
+ *    this.left = null;
+ *    this.right = null;
+ *    this.parent = null;
+ * };
+ */
+
+/**
+ * @param {_Node} node
+ * @return {_Node}
+ */
+var inorderSuccessor = function(node) {
+  if (node.right) {
+    let successor = node.right;
+    while (successor.left) {
+      successor = successor.left;
+    }
+    return successor;
+  }
+
+  let current = node;
+  while (current.parent && current.parent.right === current) {
+    current = current.parent;
+  }
+  return current.parent;
+};