Implement selection sort

lib/sort/bubble.js

@@ -26,16 +26,17 @@ function bubble(array) {
     var swapped = false;
 
     while (++index < length) {
-      var current = array[index];
-      var next = array[index + 1];
-
-      if (current > next) {
-        array[index + 1] = current;
-        array[index] = next;
+      var element = array[index];
+      // compare the adjacent elements
+      if (element > array[index + 1]) {
+        // swap elements
+        array[index] = array[index + 1];
+        array[index + 1] = element;
         swapped = true;
       }
     }
-
+    // if no number was swapped that means
+    // array is sorted now, break the loop.
     if (!swapped) {
       break;
     }

lib/sort/insertion.js

@@ -29,7 +29,9 @@ function insertion(array) {
       position = position - 1;
     }
     // insert value at hole position
-    array[position] = value;
+    if (position < i) {
+      array[position] = value;
+    }
   }
 
   return array;

lib/sort/selection.js

@@ -0,0 +1,43 @@
+
+/**
+ * Expose `selection`.
+ */
+
+module.exports = selection;
+
+/**
+ * Selection sort.
+ *
+ * @param {Array} array
+ * @returns {Array}
+ * @example
+ *
+ * selection([2, 3, 1, 5, 4]);
+ * // => [1, 2, 3, 4, 5]
+ *
+ * selection(['b', 'c', 'a', 'e', 'd']);
+ * // => ['a', 'b', 'c', 'd', 'e']
+ */
+
+function selection(array) {
+  var index = -1;
+  var length = array.length;
+
+  while (++index < length) {
+    var element = array[index]; // store element
+    var min = index; // set minimal index
+    // check the element to be minimum
+    for (var i = index + 1; i < length; i++) {
+      if (element > array[i]) {
+        min = i; // update minimum index
+      }
+    }
+    // swap the minimum element with the current element
+    if (min > index) {
+      array[index] = array[min];
+      array[min] = element;
+    }
+  }
+
+  return array;
+}

lib/sort/test/bubble-test.js

@@ -2,7 +2,10 @@ var test = require('tape');
 var bubble = require('../bubble');
 
 test('bubble(array)', function (t) {
-  t.deepEqual(bubble([2, 3, 1]), [1, 2, 3], 'should be sorted 1 2 3');
-  t.deepEqual(bubble(['b', 'c', 'a']), ['a', 'b', 'c'], 'should be sorted a b c');
+  t.deepEqual(bubble([]), [], 'should return empty array');
+  t.deepEqual(bubble([1, 2, 3, 4, 5]), [1, 2, 3, 4, 5], 'should return sorted array');
+  t.deepEqual(bubble([5, 4, 3, 2, 1]), [1, 2, 3, 4, 5], 'should be sorted 1 2 3 4 5');
+  t.deepEqual(bubble([2, 3, 1, 5, 4]), [1, 2, 3, 4, 5], 'should be sorted 1 2 3 4 5');
+  t.deepEqual(bubble(['b', 'c', 'a', 'e', 'd']), ['a', 'b', 'c', 'd', 'e'], 'should be sorted a b c d e');
   t.end();
 });

lib/sort/test/insertion-test.js

@@ -2,6 +2,9 @@ var test = require('tape');
 var insertion = require('../insertion');
 
 test('insertion(array)', function (t) {
+  t.deepEqual(insertion([]), [], 'should return empty array');
+  t.deepEqual(insertion([1, 2, 3, 4, 5]), [1, 2, 3, 4, 5], 'should return sorted array');
+  t.deepEqual(insertion([5, 4, 3, 2, 1]), [1, 2, 3, 4, 5], 'should be sorted 1 2 3 4 5');
   t.deepEqual(insertion([2, 3, 1, 5, 4]), [1, 2, 3, 4, 5], 'should be sorted 1 2 3 4 5');
   t.deepEqual(insertion(['b', 'c', 'a', 'e', 'd']), ['a', 'b', 'c', 'd', 'e'], 'should be sorted a b c d e');
   t.end();

lib/sort/test/selection-test.js

@@ -0,0 +1,11 @@
+var test = require('tape');
+var selection = require('../selection');
+
+test('selection(array)', function (t) {
+  t.deepEqual(selection([]), [], 'should return empty array');
+  t.deepEqual(selection([1, 2, 3, 4, 5]), [1, 2, 3, 4, 5], 'should return sorted array');
+  t.deepEqual(selection([5, 4, 3, 2, 1]), [1, 2, 3, 4, 5], 'should be sorted 1 2 3 4 5');
+  t.deepEqual(selection([2, 3, 1, 5, 4]), [1, 2, 3, 4, 5], 'should be sorted 1 2 3 4 5');
+  t.deepEqual(selection(['b', 'c', 'a', 'e', 'd']), ['a', 'b', 'c', 'd', 'e'], 'should be sorted a b c d e');
+  t.end();
+});