O(e + n log n) dijkstra using a priority queue

make-github-pseudonymous-again · May 6, 2014 · 4f235b4 · 4f235b4
1 parent 7b403fa
commit 4f235b4
Show file tree

Hide file tree

Showing 4 changed files with 35 additions and 35 deletions.
diff --git a/README.md b/README.md
@@ -1,7 +1,7 @@
 [gn](http://aureooms.github.io/gn)
 ==
 
-gn (graphs and networks) algorithms / data structures templates for JavaScript
+gn (graphs and networks) algorithm / adt templates for JavaScript
 
 [![Build Status](https://drone.io/github.com/aureooms/gn/status.png)](https://drone.io/github.com/aureooms/gn/latest)
 [![Coverage Status](https://coveralls.io/repos/aureooms/gn/badge.png)](https://coveralls.io/r/aureooms/gn)

diff --git a/js/src/undirected/offline/algo/sp/dijkstra.js b/js/src/undirected/offline/algo/sp/dijkstra.js
@@ -1,6 +1,6 @@
 
 
-var dijkstra_t = function(){
+var dijkstra_t = function(priority_queue_t){
 
 	var dijkstra = function(g, order, s){
 		var i, j, k, len, m, min;
@@ -19,7 +19,10 @@ var dijkstra_t = function(){
 			busy[i] = false;
 		}
 
-		var left = [];
+		var pred = function(a, b){ return dist[a[0]] < dist[b[0]]; };
+		var priority_queue = priority_queue_t(pred);
+		var left = new priority_queue();
+
 		used[s[0]] = true;
 		busy[s[0]] = true;
 
@@ -31,19 +34,7 @@ var dijkstra_t = function(){
 
 		while(left.length){
 
-			m = left[0];
-			min = dist[m[0]];
-			j = 0;
-
-			for(i = 1, len = left.length; i < len; ++i){
-				if(dist[left[i][0]] < min){
-					m = left[i];
-					min = dist[m[0]];
-					j = i;
-				}
-			}
-
-			left.splice(j, 1);
+			m = left.pop();
 			used[m[0]] = true;
 
 			g.eitr(m, function(e){

diff --git a/package.json b/package.json
@@ -1,15 +1,16 @@
 {
   "name": "gn",
-  "version": "0.0.0",
-  "description": "gn (graphs and networks) algorithms / data structures templates for JavaScript",
+  "version": "0.0.1",
+  "description": "gn (graphs and networks) algorithm / adt templates for JavaScript",
   "main": "js/index.js",
   "dependencies": {
     "recquire": "^0.0.0"
   },
   "devDependencies": {
     "qunit": "git://github.com/gotwarlost/node-qunit.git#istanbul-coverage",
     "coveralls": "^2.10.0",
-    "optimist": "^0.6.1"
+    "optimist": "^0.6.1",
+    "algo": "^0.0.3"
   },
   "scripts": {
     "test": "export DIR=node_modules/qunit/support/qunit/qunit && mkdir -p $DIR && cp support/qunit.js $DIR/ && node test/js/run.js"
@@ -22,8 +23,9 @@
     "js",
     "javascript",
     "algorithm",
-    "data structure",
+    "adt",
     "template",
+    "complexity",
     "graphs",
     "networks",
     "gn"

diff --git a/test/js/src/undirected/offline/algo/sp/dijkstra.js b/test/js/src/undirected/offline/algo/sp/dijkstra.js
@@ -1,29 +1,36 @@
 
+var algo = require('algo');
+
 var check = function(label, n, s, edges, prev, dist){
 
-test('dijkstra #' + label, function(assert){
+	test('dijkstra #' + label, function(assert){
+
+		var Graph = gn.dense_graph_t();
+
+		var priority_queue_t = function(pred){
+			return algo.lazy_binomial_queue_t(pred, algo.opt_t);
+		};
 
-	var Graph = gn.dense_graph_t();
-	var dijkstra = gn.dijkstra_t();
+		var dijkstra = gn.dijkstra_t(priority_queue_t);
 
-	var g = new Graph();
-	var i = n;
+		var g = new Graph();
+		var i = n;
 
-	var v = new Array(i);
+		var v = new Array(i);
 
-	while(i--) v[n-i-1] = g.vadd();
+		while(i--) v[n-i-1] = g.vadd();
 
-	for(var j = 0; j < edges.length; ++j){
-		var e = edges[j];
-		g.eadd(v[e[0]], v[e[1]], e[2]);		
-	}
+		for(var j = 0; j < edges.length; ++j){
+			var e = edges[j];
+			g.eadd(v[e[0]], v[e[1]], e[2]);		
+		}
 
-	var sp = dijkstra(g, n, v[s]);
+		var sp = dijkstra(g, n, v[s]);
 
-	deepEqual(prev, sp[0], 'prev');
-	deepEqual(dist, sp[1], 'dist');
+		deepEqual(prev, sp[0], 'prev');
+		deepEqual(dist, sp[1], 'dist');
 
-});
+	});
 
 };