From 6da8c62e159f2b497ddb93f9ad1511d90df0949f Mon Sep 17 00:00:00 2001
From: Adrian Mejia <admejiar@cisco.com>
Date: Mon, 30 Mar 2020 16:30:25 -0400
Subject: [PATCH] :wrench: chore (lab): solve the problem

---
 lab/exercises/10-mixed/critical-routers.js    | 27 ++++++---
 .../10-mixed/critical-routers.spec.js         | 57 ++++++++++++++++++-
 2 files changed, 73 insertions(+), 11 deletions(-)

diff --git a/lab/exercises/10-mixed/critical-routers.js b/lab/exercises/10-mixed/critical-routers.js
index 39458cf1..d112b1f9 100644
--- a/lab/exercises/10-mixed/critical-routers.js
+++ b/lab/exercises/10-mixed/critical-routers.js
@@ -3,6 +3,10 @@
  * A router is considered critical if when they are removed,
  * other routers lose connection to other routers different from the one removed.
  *
+ * @runtime O(|E| * |V|^3)
+ * @space O(|E| + |V|)
+ * @pomodoro IIII (2h)
+ *
  * @param {number} numRouters - The number of routers connected in a data center >= 3.
  * @param {number} numLinks - The number of links.
  * @param {[[number, number]]} links - The pair of routers connected by the link.
@@ -15,21 +19,26 @@ function criticalRouters(numRouters, numLinks, links) {
   // console.log({graph});
 
   for (let curr = 1; curr <= numRouters; curr++) {
-    for (let i = 1; i <= numRouters; i++) {
-      for (let j = 1; j <= numRouters; j++) {
-        if (curr === i || curr === j || i === j) { continue; }
-        if (!isConnected(graph, i, j, curr)) {
-          critical.push(curr);
-          i++;
-          break;
-        }
-      }
+    if (isCritical(graph, curr)) {
+      critical.push(curr);
     }
   }
 
   return critical;
 }
 
+function isCritical(graph, curr) {
+  for (let i = 1; i <= graph.size; i++) {
+    for (let j = 1; j <= graph.size; j++) {
+      if (curr === i || curr === j || i === j) { continue; }
+      if (!isConnected(graph, i, j, curr)) {
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
 function addEdge(graph, from, to) {
   // console.log('addEdge', {graph, from, to});
   const adjacents = graph.get(from);
diff --git a/lab/exercises/10-mixed/critical-routers.spec.js b/lab/exercises/10-mixed/critical-routers.spec.js
index c8023cfe..c4ec5597 100644
--- a/lab/exercises/10-mixed/critical-routers.spec.js
+++ b/lab/exercises/10-mixed/critical-routers.spec.js
@@ -2,10 +2,63 @@
 const critialRouters = require('./critical-routers');
 
 describe('Critical Routers', () => {
-  it('should work', () => {
+  it('should work with daisy chain nodes', () => {
+    const numRouters = 3;
+    const numLinks = 3;
+    const links = [
+      [1, 2],
+      [2, 3],
+      [3, 1],
+    ];
+    expect(critialRouters(numRouters, numLinks, links)).toEqual([]);
+  });
+
+  it('should work with 7 nodes', () => {
     const numRouters = 7;
     const numLinks = 7;
-    const links = [[1, 2], [1, 3], [2, 4], [3, 4], [3, 6], [6, 7], [4, 5]];
+    const links = [
+      [1, 2],
+      [1, 3],
+      [2, 4],
+      [3, 4],
+      [3, 6],
+      [6, 7],
+      [4, 5],
+    ];
     expect(critialRouters(numRouters, numLinks, links)).toEqual([3, 4, 6]);
   });
+
+  it('should work with 6 nodes', () => {
+    const numRouters = 6;
+    const numLinks = 5;
+    const links = [
+      [1, 2],
+      [2, 3],
+      [3, 4],
+      [4, 5],
+      [3, 6],
+    ];
+    expect(critialRouters(numRouters, numLinks, links)).toEqual([2, 3, 4]);
+  });
+
+  it('should work with 10 nodes', () => {
+    const numRouters = 10;
+    const numLinks = 13;
+    const links = [
+      [1, 2],
+      [1, 3],
+      [2, 3],
+      [3, 4],
+      [4, 5],
+      [4, 6],
+      [5, 6],
+      [5, 7],
+      [6, 7],
+      [7, 8],
+      [8, 9],
+      [8, 10],
+      [9, 10],
+    ];
+    expect(critialRouters(numRouters, numLinks, links)).toEqual([3, 4, 7, 8]);
+  });
 });