Add shellSort

src/sort/shell/shellSort.spec.ts

@@ -0,0 +1,30 @@
+import shellSort from './shellSort';
+
+describe('shell sort', () => {
+  it('should return an empty array when the array for sorting is empty', () => {
+    const arrayToSort: number[] = [];
+    const expectedArray: number[] = [];
+    expect(shellSort(arrayToSort))
+      .toEqual(expectedArray);
+  });
+
+  it('should return an array with the element', () => {
+    const arrayToSort: number[] = [14];
+    const expectedArray: number[] = [14];
+    expect(shellSort(arrayToSort))
+      .toEqual(expectedArray);
+  });
+
+  it('should return an array with two elements sorted from lowest to highest', () => {
+    const arrayToSort = [65, 43];
+    const expectedArray = [43, 65];
+    expect(shellSort(arrayToSort))
+      .toEqual(expectedArray);
+  });
+
+  it('should return an array sorted from lowest to highest', () => {
+    const arrayToSort = [43, 65, 44, 12, 67, 1, 9, 33, 21];
+    const expectedArray = [1, 9, 12, 21, 33, 43, 44, 65, 67];
+    expect(shellSort(arrayToSort)).toEqual(expectedArray);
+  });
+});

src/sort/shell/shellSort.ts

@@ -0,0 +1,19 @@
+export default function shellSort(array: number[]): number[] {
+  const introducedArray = array;
+  const n = introducedArray.length;
+
+  for (let gap = Math.floor(n / 2); gap > 0; gap = Math.floor(gap / 2)) {
+    for (let i = gap; i < n; i += 1) {
+      const temp = introducedArray[i];
+
+      let j;
+      for (j = i; j >= gap && introducedArray[j - gap] > temp; j -= gap) {
+        introducedArray[j] = introducedArray[j - gap];
+      }
+
+      introducedArray[j] = temp;
+    }
+  }
+
+  return introducedArray;
+}