4.4 is tree blanced. my solution

Author: amejiarosario

src/trees-and-graphs/is-balanced.js

@@ -0,0 +1,23 @@
+function isBalanced(root) {
+  // find tree's leaves' levels
+  const leavesDepths = getLeavesDepths(root).sort();
+
+  // TODO: check for empty trees, and that has less than 2 leaves
+
+  // if any leave depth is bigger than 2 than any other, then is not balanced
+  return leavesDepths[leavesDepths.length -1] - leavesDepths[leavesDepths.length -2] < 2;
+}
+
+function getLeavesDepths(node, level = 0, leavesDepths = []) {
+  if(!node.adjacents.length) {
+    leavesDepths.push(level);
+  }
+
+  node.adjacents.forEach(function (adj) {
+    getLeavesDepths(adj, level+1, leavesDepths);
+  });
+
+  return leavesDepths;
+}
+
+module.exports = isBalanced;

src/trees-and-graphs/is-balanced.spec.js

@@ -0,0 +1,33 @@
+const expect = require('chai').expect;
+const Node = require('./graph').Node;
+const Graph = require('./graph').Graph;
+const isBalanced = require('./is-balanced');
+
+describe('Graph: is balanced ?', function () {
+  let graph;
+
+  beforeEach(function () {
+    graph = new Graph();
+  });
+
+  it('should return true when is balanced and complete', function () {
+    graph.add(0, 1);
+    const root = graph.add(0, 2);
+    expect(isBalanced(root)).to.equal(true);
+  });
+
+  it('should return true when is balanced and not complete', function () {
+    const root = graph.add(0, 1);
+    graph.add(0, 2);
+    graph.add(2, 3);
+    expect(isBalanced(root)).to.equal(true);
+  });
+
+  it('should return false when is not balanced', function () {
+    const root = graph.add(0, 1);
+    graph.add(0, 2);
+    graph.add(2, 3);
+    graph.add(3, 4);
+    expect(isBalanced(root)).to.equal(false);
+  });
+});