From 9fda2c094c7fd26f4ca73fff981fc4934c1e5f18 Mon Sep 17 00:00:00 2001
From: Hussein El Motayam <husseinelmotayam@gmail.com>
Date: Wed, 11 Mar 2020 19:31:53 +0200
Subject: [PATCH] Support unmapped adjacency list indices #14

---
 johnson.js   |  2 +-
 test/test.js | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/johnson.js b/johnson.js
index f897a51..9dcaf27 100644
--- a/johnson.js
+++ b/johnson.js
@@ -70,7 +70,7 @@ module.exports = function findCircuits(edges, cb) {
     function subgraph(minId) {
       // Remove edges with indice smaller than minId
         for(var i = 0; i < edges.length; i++) {
-            if(i < minId) edges[i] = [];
+            if(i < minId || !edges[i]) edges[i] = [];
             edges[i] = edges[i].filter(function(i) {
                 return i >= minId;
             });
diff --git a/test/test.js b/test/test.js
index 1623fa6..c2cde8a 100644
--- a/test/test.js
+++ b/test/test.js
@@ -43,6 +43,25 @@ test('find elementarty circuits in', function(t) {
         t.end();
     });
 
+    t.test('another simple directed graph with orphaned nodes', function(t) {
+    //       V4      V2
+    // +-<---o---<---o
+    // |             |
+    // o V0          ^      o V3
+    // |           V1|
+    // +------>------o
+        var g = [];
+        g[0] = [1];
+        g[1] = [2];
+    // g[3] is unmapped
+        g[2] = [4];
+        g[4] = [0];
+
+        var circuits = findCircuits(g);
+        t.deepEqual(circuits, [[0, 1, 2, 4, 0]]);
+        t.end();
+    });
+
     t.test('another simple directed graph with callback', function(t) {
         var g = [
           [1],