DS Trees Complete Course

Author: HuXn-WebDev

7. Tree/1. BST/index.js

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+class Node {
+  constructor(value) {
+    this.value = value;
+    this.left = null;
+    this.right = null;
+  }
+}
+
+class BST {
+  constructor() {
+    this.root = null;
+  }
+
+  insert(value) {
+    const newNode = new Node(value);
+    if (this.root === null) {
+      this.root = newNode;
+      return this;
+    }
+
+    let temp = this.root;
+    while (true) {
+      if (newNode.value === temp.value) return undefined;
+      if (newNode.value < temp.value) {
+        if (temp.left === null) {
+          temp.left = newNode;
+          return this;
+        } else {
+          temp = temp.left;
+        }
+      } else {
+        if (temp.right === null) {
+          temp.right = newNode;
+          return this;
+        }
+        temp = temp.right;
+      }
+    }
+  }
+
+  includes(value) {
+    if (!this.root) return false;
+
+    let temp = this.root;
+    while (temp) {
+      if (value < temp.value) {
+        temp = temp.left;
+      } else if (value > temp.value) {
+        temp = temp.right;
+      } else if (value === temp.value) {
+        return true;
+      }
+    }
+    return false;
+  }
+}
+
+const tree = new BST();
+tree.insert(5);
+tree.insert(8);
+tree.insert(3);
+tree.insert(1);
+tree.insert(7);
+tree.insert(9);
+console.log(tree.includes(9));

7. Tree/2. Recursion/index.js

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+// ------------------ Example 1
+function countDown(number) {
+  if (number === 0) {
+    console.log("And finally the stopping point! 🥂");
+    return;
+  }
+
+  console.log(number);
+  countDown(number - 1);
+}
+
+countDown(5);
+
+// ------------------ Example 2
+function factorial(number) {
+  if (number === 0) {
+    return 1;
+  }
+
+  return number * factorial(number - 1);
+  // return number === 0 ? 1 : number * factorial(number - 1);
+}
+
+console.log(factorial(4));

7. Tree/3. Tree Traversal/index.js

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+class Node {
+  constructor(value) {
+    this.value = value;
+    this.left = null;
+    this.right = null;
+  }
+}
+
+class BST {
+  constructor() {
+    this.root = null;
+  }
+
+  insert(value) {
+    const newNode = new Node(value);
+    if (this.root === null) {
+      this.root = newNode;
+      return this;
+    }
+
+    let temp = this.root;
+    while (true) {
+      if (newNode.value === temp.value) return undefined;
+      if (newNode.value < temp.value) {
+        if (temp.left === null) {
+          temp.left = newNode;
+          return this;
+        } else {
+          temp = temp.left;
+        }
+      } else {
+        if (temp.right === null) {
+          temp.right = newNode;
+          return this;
+        }
+        temp = temp.right;
+      }
+    }
+  }
+
+  dfs() {
+    let current = this.root;
+    let queue = [];
+    let data = [];
+
+    queue.push(current);
+
+    while (queue.length) {
+      current = queue.shift();
+      data.push(current.value);
+
+      if (current.left) queue.push(current.left);
+      if (current.right) queue.push(current.right);
+    }
+    return data;
+  }
+
+  dfsPreOrder(node = this.root, data = []) {
+    if (node === null) return data;
+    console.log("--------", data);
+
+    data.push(node.value);
+    if (node.left) this.dfsPreOrder(node.left, data);
+    if (node.right) this.dfsPreOrder(node.right, data);
+    return data;
+  }
+
+  dfsPostOrder(node = this.root, data = []) {
+    if (node === null) return data;
+    if (node.left) this.dfsPostOrder(node.left, data);
+    if (node.right) this.dfsPostOrder(node.right, data);
+    data.push(node.value);
+    return data;
+  }
+
+  dfsInOrder(node = this.root, data = []) {
+    if (node === null) return data;
+    this.dfsInOrder(node.left, data);
+    data.push(node.value);
+    this.dfsInOrder(node.right, data);
+    return data;
+  }
+}
+
+const tree = new BST();
+tree.insert(5);
+tree.insert(8);
+tree.insert(3);
+tree.insert(1);
+tree.insert(7);
+tree.insert(9);
+console.log(tree.dfs());
+console.log(tree.dfsPreOrder());
+console.log(tree.dfsPostOrder());
+console.log(tree.dfsInOrder());