From 2dab36b36edd1864db82a266ab2044c22cca0330 Mon Sep 17 00:00:00 2001
From: Loosetooth <loosetooth@protonmail.com>
Date: Sat, 1 Feb 2025 23:50:01 +0100
Subject: [PATCH] add kata

---
 5kyu/count-ip-addresses/description.md |  8 ++++++++
 5kyu/count-ip-addresses/solution.ts    | 17 +++++++++++++++++
 5kyu/count-ip-addresses/tests.ts       | 11 +++++++++++
 3 files changed, 36 insertions(+)
 create mode 100644 5kyu/count-ip-addresses/description.md
 create mode 100644 5kyu/count-ip-addresses/solution.ts
 create mode 100644 5kyu/count-ip-addresses/tests.ts

diff --git a/5kyu/count-ip-addresses/description.md b/5kyu/count-ip-addresses/description.md
new file mode 100644
index 0000000..9eef242
--- /dev/null
+++ b/5kyu/count-ip-addresses/description.md
@@ -0,0 +1,8 @@
+Implement a function that receives two IPv4 addresses, and returns the number of addresses between them (including the first one, excluding the last one).
+
+All inputs will be valid IPv4 addresses in the form of strings. The last address will always be greater than the first one.
+
+Examples
+* With input "10.0.0.0", "10.0.0.50"  => return   50 
+* With input "10.0.0.0", "10.0.1.0"   => return  256 
+* With input "20.0.0.10", "20.0.1.0"  => return  246
diff --git a/5kyu/count-ip-addresses/solution.ts b/5kyu/count-ip-addresses/solution.ts
new file mode 100644
index 0000000..52d79a4
--- /dev/null
+++ b/5kyu/count-ip-addresses/solution.ts
@@ -0,0 +1,17 @@
+/**
+ * Regards an IP address as a number with 4 digits.
+ * Each digit can be between 0 and 255.
+ * The result of this function is the total number of possible IPs 'lower' than the given IP.
+ */
+const ipToNum = (ip: string): number => {
+  const digits = ip.split('.').map(Number) as [number, number, number, number];
+  console.log(digits);
+  if(digits.length !== 4) {
+    throw new Error('Invalid IP address');
+  }
+  return digits.reduce((sum, digit) => sum * 256 + digit, 0);
+}
+
+export function ipsBetween(start: string, end: string): number {
+  return ipToNum(end) - ipToNum(start);
+}
\ No newline at end of file
diff --git a/5kyu/count-ip-addresses/tests.ts b/5kyu/count-ip-addresses/tests.ts
new file mode 100644
index 0000000..e4d0580
--- /dev/null
+++ b/5kyu/count-ip-addresses/tests.ts
@@ -0,0 +1,11 @@
+// See https://www.chaijs.com for how to use Chai.
+import { assert } from "chai";
+import { ipsBetween } from "./solution";
+
+// TODO Add your tests here
+describe("example", function() {
+  it("test", function() {
+    assert.equal(ipsBetween("10.0.0.0", "10.0.0.50"), 50, 'ipsBetween("10.0.0.0", "10.0.0.50")');
+    assert.equal(ipsBetween("20.0.0.10", "20.0.1.0"), 246, 'ipsBetween("20.0.0.10", "20.0.1.0")');
+  });
+});
\ No newline at end of file