algorithm: insertion sort (#26)

* feat: add insertionsort algorithm

* chore: fix variable declaration

Author: gefgu

Sorts/InsertionSort.ts

@@ -0,0 +1,22 @@
+/**
+ * @function insertionSort
+ * @description simple sortion algorithm for a small number of elements. It compares the `key` element with the previous elements. If the previous elements are greater than the `key` element, then you move the previous element to the next position.
+ * @param {number[]} num - The input array
+ * @return {number[]} - The sorted array.
+ * @see [Insertion Sort](https://www.freecodecamp.org/news/sorting-algorithms-explained-with-examples-in-python-java-and-c#insertion-sort)
+ * @example BinaryConvert([8, 3, 5, 1, 4, 2]) = [1, 2, 3, 4, 5, 8]
+ */
+
+export const insertionSort = (arr: number[]): number[] => {
+  for (let i = 1; i < arr.length; i++) {
+    const temp = arr[i];
+    let j = i - 1;
+    while (j >= 0 && arr[j] > temp) {
+      arr[j + 1] = arr[j];
+      j--;
+    }
+    arr[j + 1] = temp;
+  }
+
+  return arr;
+};

Sorts/test/InsertionSort.test.ts

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+import { insertionSort } from "../InsertionSort";
+
+describe("Insertion Sort", () => {
+  it("should return the correct value for average case", () => {
+    expect(insertionSort([8, 3, 5, 1, 4, 2])).toStrictEqual([1, 2, 3, 4, 5, 8]);
+  });
+
+  it("should return the correct value for worst case", () => {
+    expect(insertionSort([9, 8, 7, 6, 5, 4, 3, 2, 1])).toStrictEqual([1, 2, 3, 4, 5, 6, 7, 8, 9]);
+  });
+
+  it("should return the correct value for best case", () => {
+    expect(insertionSort([1, 2, 3, 4, 5, 8])).toStrictEqual([1, 2, 3, 4, 5, 8]);
+  });
+});