Data Structures: Delete a Node with Two Children in a Binary Search Tree

Data Structures/bstDeleteTwoChildrenNode.js

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+// https://www.freecodecamp.org/learn/coding-interview-prep/data-structures/delete-a-node-with-one-child-in-a-binary-search-tree
+
+var displayTree = (tree) => console.log(JSON.stringify(tree, null, 2));
+function Node(value) {
+  this.value = value;
+  this.left = null;
+  this.right = null;
+}
+
+function BinarySearchTree() {
+  this.root = null;
+  // Only change code below this line
+  this.remove = (value) => {
+    let parent = null;
+    let node = this.root;
+    while (node !== null && node.value !== value) {
+      parent = node;
+      if (node.value < value) {
+        node = node.right;
+      } else {
+        node = node.left;
+      }
+    }
+    if (node === null) return null;
+    let child = null;
+    if (node.left !== null && node.right === null) child = node.left;
+    else if (node.left === null && node.right !== null) child = node.right;
+    else if (node.left !== null && node.right !== null) {
+      let smallestRightNodeParent = node;
+      let smallestRightNode = node.right;
+      while (smallestRightNode.left !== null) {
+        smallestRightNodeParent = smallestRightNode;
+        smallestRightNode = smallestRightNode.left;
+      }
+      node.value = smallestRightNode.value;
+      if (smallestRightNodeParent !== node)
+        smallestRightNodeParent.left = smallestRightNode.right;
+      else node.right = null;
+      return;
+    }
+    if (parent === null) this.root = child;
+    else if (parent.value < value) {
+      parent.right = child;
+    } else {
+      parent.left = child;
+    }
+  };
+}