4.3 list of depths solution and tests

Author: amejiarosario

src/trees-and-graphs/list-of-depths.js

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+const Queue = require('../stacks-and-queues/queue');
+const LinkedList = require('../linked-list/linkedlist');
+
+function listOfDepths(root) {
+  const queue = new Queue();
+  const list = [];
+  let depth = 0;
+
+  if(!root) return list;
+
+  queue.add(root);
+  queue.add('*');
+
+  while(!queue.isEmpty()) {
+    if(queue.peek() === '*') {
+      queue.remove();
+      depth++;
+
+      if(queue.isEmpty()) {
+        continue;
+      } else {
+        queue.add('*');
+      }
+    }
+
+    const node = queue.remove();
+    add(list, depth, node.data);
+
+    node.adjacents.forEach(function (adj) {
+      queue.add(adj);
+    });
+  }
+
+  return list;
+}
+
+function add(list, depth, data) {
+  list[depth] = list[depth] || new LinkedList();
+  list[depth].addLast(data);
+}
+
+module.exports = listOfDepths;

src/trees-and-graphs/list-of-depths.spec.js

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+const expect = require('chai').expect;
+const Node = require('./graph').Node;
+const listOfDepths = require('./list-of-depths');
+
+describe('Graph: List of depths', function () {
+
+  it('should work with 0 elements', function () {
+    let list = listOfDepths();
+    expect(list.length).to.equal(0);
+  });
+
+
+  it('should work with 1 element', function () {
+    let tree = new Node('a');
+    let list = listOfDepths(tree);
+    expect(list.length).to.equal(1);
+    expect(list[0].toString()).to.equal('a');
+  });
+
+  it('should work with tree depth 2', function () {
+    let tree = new Node('a');
+    tree.adjacents = [new Node('b'), new Node('c')];
+
+    let list = listOfDepths(tree);
+    expect(list.length).to.equal(2);
+    expect(list[1].toString()).to.equal('b -> c');
+  });
+
+  it('should work with tree depth 3', function () {
+    let a = new Node('a'),
+      b = new Node('b'),
+      c = new Node('c'),
+      d = new Node('d'),
+      e = new Node('e'),
+      f = new Node('f'),
+      g = new Node('g');
+
+    b.adjacents = [d, e];
+    c.adjacents = [f, g];
+    a.adjacents = [b, c];
+
+    let list = listOfDepths(a);
+    expect(list.length).to.equal(3);
+    expect(list[2].toString()).to.equal('d -> e -> f -> g');
+  });
+});