Radix sort implementation.

index.html

@@ -105,6 +105,7 @@
     <script type='text/javascript' src='js/shellsort.js'></script>
     <script type='text/javascript' src='js/selectionsort.js'></script>
     <script type='text/javascript' src='js/bubblesort.js'></script>
+    <script type='text/javascript' src='js/radixsort.js'></script>
 
     <script type='text/javascript'>
         var dump = function(arr) {
@@ -116,7 +117,7 @@
             return d.join(',');
         }
 
-        var SS = new Bubblesort();
+        var SS = new RadixSort();
 
         var data = SS.generate(15);
         console.log('DATA: ' + dump(data));
@@ -125,7 +126,7 @@
         console.log('SHUFFLED: ' + dump(shuffled));
 
         var ordered = Object.create(shuffled);
-        SS.sort(ordered, 0, ordered.length - 1);
+        ordered = SS.sort(ordered, 0, ordered.length - 1);
         console.log('ORDERED: ' + dump(ordered));
 
 

js/bubblesort.js

@@ -15,6 +15,7 @@ Bubblesort.prototype.sort = function(arr) {
     var swapped = false;
     var len = arr.length;
 
+    // NOTE this starts at the beginning of the array each time
     for (i = 1; i < len; i++) {
         if (arr[i - 1].value > arr[i].value) {
             this.swap(arr, i, i - 1);

js/radixsort.js

@@ -0,0 +1,64 @@
+/**
+ *
+ */
+var RadixSort = function() {
+    this.instructions = [];
+};
+
+RadixSort.prototype = Object.create(Sorter.prototype);
+
+/**
+ *
+ */
+RadixSort.prototype.sort = function(arr) {
+    var max = 0;
+    var len = arr.length;
+    var tmp = arr;
+
+    // Find max
+    for (var i = 0; i < len; i++) {
+        if (max < arr[i].value) {
+            max = arr[i].value;
+        }
+    }
+
+    // Run through digit sort for as many digits as in max
+    var digits = max.toString().length;
+    for (var i = 1; i <= digits; i++) {
+        tmp = this.sortByDigit(tmp, i);
+    }
+
+    return tmp;
+};
+
+/**
+ *
+ */
+RadixSort.prototype.sortByDigit = function(arr, digit) {
+    var len = arr.length;
+    var val = null;
+    var buckets = [];
+    var result = [];
+
+    // Sort into buckets
+    for (var i = 0; i < len; i++) {
+        // Remove more significant digits, then round down all less significant digits.
+        val = arr[i].value % Math.pow(10, digit);
+        val = Math.floor((val / Math.pow(10, digit - 1)));
+
+        if (buckets[val] === undefined) {
+            buckets[val] = [];
+        }
+
+        buckets[val].push(arr[i]);
+    }
+
+    // Concat sorted buckets
+    for (var j = 0; j < 10; j++) {
+        if (buckets[j] !== undefined) {
+            result = result.concat(buckets[j]);
+        }
+    }
+
+    return result;
+};