From 3b7d0b4574fbbe8c3bd0fdcc58dc5133edb90c6f Mon Sep 17 00:00:00 2001
From: Lorenzo Iovino <thisloke@gmail.com>
Date: Wed, 24 Jan 2024 18:55:09 +0100
Subject: [PATCH] challenge ctci-array-left-rotation

---
 .gitignore                                      |  3 ++-
 .../ctci-array-left-rotation.spec.ts            | 17 +++++++++++++++++
 .../ctci-array-left-rotation.ts                 | 15 +++++++++++++++
 3 files changed, 34 insertions(+), 1 deletion(-)
 create mode 100644 src/ctci-array-left-rotation/ctci-array-left-rotation.spec.ts
 create mode 100644 src/ctci-array-left-rotation/ctci-array-left-rotation.ts

diff --git a/.gitignore b/.gitignore
index a375727..0573864 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 node_modules
 build
-.idea
\ No newline at end of file
+.idea
+.DS_STORE
\ No newline at end of file
diff --git a/src/ctci-array-left-rotation/ctci-array-left-rotation.spec.ts b/src/ctci-array-left-rotation/ctci-array-left-rotation.spec.ts
new file mode 100644
index 0000000..97b60fc
--- /dev/null
+++ b/src/ctci-array-left-rotation/ctci-array-left-rotation.spec.ts
@@ -0,0 +1,17 @@
+import {describe, it} from "node:test";
+import assert = require("node:assert");
+import {rotLeft} from "./ctci-array-left-rotation";
+
+describe("Ctci Array Left Rotation", () => {
+    describe("rotLeft", () => {
+        it("an empty array return itself ", () => {
+            assert.deepStrictEqual(rotLeft([], 100), [])
+            assert.deepStrictEqual(rotLeft([], 1), [])
+            assert.deepStrictEqual(rotLeft([], 0), [])
+        })
+
+        it("rotate an array of X position should return the array rotated left by X position", () => {
+            assert.deepStrictEqual(rotLeft([1, 2, 3, 4, 5], 4), [5, 1, 2, 3, 4]);
+        })
+    });
+})
\ No newline at end of file
diff --git a/src/ctci-array-left-rotation/ctci-array-left-rotation.ts b/src/ctci-array-left-rotation/ctci-array-left-rotation.ts
new file mode 100644
index 0000000..0bb9f89
--- /dev/null
+++ b/src/ctci-array-left-rotation/ctci-array-left-rotation.ts
@@ -0,0 +1,15 @@
+export function rotLeft(a: Array<number>, d: number): Array<number> {
+    if(a.length === 0) {
+        return [];
+    }
+
+    if(a.length == d) {
+        return a.reverse();
+    }
+
+    const firstElements = a.slice(0, d)
+    a.splice(0, d);
+    a = a.concat(firstElements);
+
+    return a;
+}
\ No newline at end of file