Added Tree DS code in JS

itssHimanshuAgarwal · itssHimanshuAgarwal · commit b82bd4fa7dde · 2020-10-24T12:44:12.000+05:30
diff --git a/Tree/index.js b/Tree/index.js
@@ -0,0 +1,48 @@
+// --- Directions
+// 1) Create a node class.  The constructor
+// should accept an argument that gets assigned
+// to the data property and initialize an
+// empty array for storing children. The node
+// class should have methods 'add' and 'remove'.
+// 2) Create a tree class. The tree constructor
+// should initialize a 'root' property to null.
+// 3) Implement 'traverseBF' and 'traverseDF'
+// on the tree class.  Each method should accept a
+// function that gets called with each element in the tree
+
+class Node {
+  constructor(data) {
+    this.data = data;
+    this.children = [];
+  }
+  add(data) {
+    this.children.push(new Node(data));
+  }
+  remove(data) {
+    this.children = this.children.filter((node) => {
+      return node.data !== data;
+    });
+  }
+}
+class Tree {
+  constructor() {
+    this.root = null;
+  }
+}
+traverseBF(fn){
+  const arr=[this.root];
+  while(arr.length){
+    const node = arr.shift();
+    arr.push(...node.children);
+    fn(node);
+  }
+}
+traverseDF(fn){
+  const arr =[this.root];
+  while(arr.length){
+    const node=arr.shift();
+    arr.unshift(...node.children)
+    fn(node);
+  }
+}
+module.exports = { Tree, Node };
diff --git a/Tree/test.js b/Tree/test.js
@@ -0,0 +1,67 @@
+const T = require('./index');
+const Node = T.Node;
+const Tree = T.Tree;
+
+describe('Node', () => {
+  test('Node is a constructor', () => {
+    expect(typeof Node.prototype.constructor).toEqual('function');
+  });
+
+  test('Node has a data and children properties', () => {
+    const n = new Node('a');
+    expect(n.data).toEqual('a');
+    expect(n.children.length).toEqual(0);
+  });
+
+  test('Node can add children', () => {
+    const n = new Node('a');
+    n.add('b');
+    expect(n.children.length).toEqual(1);
+    expect(n.children[0].children).toEqual([]);
+  });
+
+  test('Node can remove children', () => {
+    const n = new Node('a');
+    n.add('b');
+    expect(n.children.length).toEqual(1);
+    n.remove('b');
+    expect(n.children.length).toEqual(0);
+  });
+});
+
+describe.skip('Tree', () => {
+  test('starts empty', () => {
+    const t = new Tree();
+    expect(t.root).toEqual(null);
+  });
+
+  test('Can traverse bf', () => {
+    const letters = [];
+    const t = new Tree();
+    t.root = new Node('a');
+    t.root.add('b');
+    t.root.add('c');
+    t.root.children[0].add('d');
+
+    t.traverseBF(node => {
+      letters.push(node.data);
+    });
+
+    expect(letters).toEqual(['a', 'b', 'c', 'd']);
+  });
+
+  test('Can traverse DF', () => {
+    const letters = [];
+    const t = new Tree();
+    t.root = new Node('a');
+    t.root.add('b');
+    t.root.add('d');
+    t.root.children[0].add('c');
+
+    t.traverseDF(node => {
+      letters.push(node.data);
+    });
+
+    expect(letters).toEqual(['a', 'b', 'c', 'd']);
+  });
+});
