Add shellsort

Author: benoitvallon

sorting-algorithms-in-javascript/shellsort-counters.js

@@ -0,0 +1,33 @@
+// sample of arrays to sort
+var arrayRandom = [9, 2, 5, 6, 4, 3, 7, 10, 1, 8];
+var arrayOrdered = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
+var arrayReversed = [10, 9, 8, 7, 6, 5, 4, 3, 2, 1];
+
+// gaps
+var gaps = [701, 301, 132, 57, 23, 10, 4, 1];
+
+function shellsort(array) {
+  var countOuter = 0;
+  var countInner = 0;
+  var countSwap = 0;
+
+  for(var g = 0; g < gaps.length; g++) {
+    var gap = gaps[g];
+    for(var i = gap; i < array.length; i++) {
+      countOuter++;
+      var temp = array[i];
+      for(var j = i; j >= gap && array[j - gap] > temp; j -= gap) {
+        countInner++;
+        countSwap++;
+        array[j] = array[j - gap];
+      }
+      array[j] = temp;
+    }
+  }
+  console.log('outer:', countOuter, 'inner:', countInner, 'swap:', countSwap);
+  return array;
+}
+
+shellsort(arrayRandom.slice()); // => outer: 15 inner: 11 swap: 11
+shellsort(arrayOrdered.slice()); // => outer: 15 inner: 0 swap: 0
+shellsort(arrayReversed.slice()); // => outer: 15 inner: 13 swap: 13

sorting-algorithms-in-javascript/shellsort.js

@@ -0,0 +1,21 @@
+// array to sort
+var array = [9, 2, 5, 6, 4, 3, 7, 10, 1, 8];
+
+// gaps
+var gaps = [701, 301, 132, 57, 23, 10, 4, 1];
+
+function shellsort(array) {
+  for(var g = 0; g < gaps.length; g++) {
+    var gap = gaps[g];
+    for(var i = gap; i < array.length; i++) {
+      var temp = array[i];
+      for(var j = i; j >= gap && array[j - gap] > temp; j -= gap) {
+        array[j] = array[j - gap];
+      }
+      array[j] = temp;
+    }
+  }
+  return array;
+}
+
+console.log(shellsort(array)); // => [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ]