Data Structures: Use Breadth First Search in a Binary Search Tree

Data Structures/bstBFS.js

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+// https://www.freecodecamp.org/learn/coding-interview-prep/data-structures/use-breadth-first-search-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.bfs = (order) => {
+    if (this.root === null) return null;
+    const values = [];
+    let q = [this.root];
+    let nextQ = [];
+    while (q.length) {
+      for (let node of q) {
+        values.push(node.value);
+        order(node, nextQ);
+      }
+      q = nextQ;
+      nextQ = [];
+    }
+    return values;
+  };
+
+  this.levelOrder = () => {
+    return this.bfs((node, nextQ) => {
+      if (node.left !== null) nextQ.push(node.left);
+      if (node.right !== null) nextQ.push(node.right);
+    });
+  };
+
+  this.reverseLevelOrder = () => {
+    return this.bfs((node, nextQ) => {
+      if (node.right !== null) nextQ.push(node.right);
+      if (node.left !== null) nextQ.push(node.left);
+    });
+  };
+  // Only change code above this line
+}