One two skip a few

.vscode/tasks.json

@@ -5,7 +5,7 @@
 			"id": "name",
 			"type": "promptString",
 			"description": "New problem name",
-			"default": "NEW_PROBLEM_X"
+			"default": "New-Prbolem-Name"
 		}
 	],
 	"tasks": [

Problems/One-Two-Skip-A-Few/One-Two-Skip-A-Few.test.ts

@@ -0,0 +1,32 @@
+import { describe, expect, it } from "vitest";
+import howManyMissing from "./solver";
+
+describe("Returns the correct number of missing numbers", () => {
+	it("should return 4 for [1, 2, 3, 8, 9]", () => {
+		expect(howManyMissing([1, 2, 3, 8, 9])).toEqual(4);
+	});
+
+	it("should return 1 for [1, 3]", () => {
+		expect(howManyMissing([1, 3])).toEqual(1);
+	});
+
+	it("should return 2 for [7, 10, 11, 12]", () => {
+		expect(howManyMissing([7, 10, 11, 12])).toEqual(2);
+	});
+
+	it("should return 5 for [1, 3, 5, 7, 9, 11]", () => {
+		expect(howManyMissing([1, 3, 5, 7, 9, 11])).toEqual(5);
+	});
+
+	it("should return 0 for [5, 6, 7, 8]", () => {
+		expect(howManyMissing([5, 6, 7, 8])).toEqual(0);
+	});
+
+	it("should return 0 for []", () => {
+		expect(howManyMissing([])).toEqual(0);
+	});
+
+	it("should return 100 for [5, 6, 86, 87, 90, 97, 111]", () => {
+		expect(howManyMissing([5, 6, 86, 87, 90, 97, 111])).toEqual(100);
+	});
+});

Problems/One-Two-Skip-A-Few/README.md

@@ -0,0 +1,43 @@
+# One-Two-Skip-A-Few
+
+You are given a sorted list `l` of length `n`, for example `[1, 3, 4, 5, 7]`.
+
+Your task is to determine how many numbers are missing between `l[0]` and `l[n - 1]`.  
+In other words, count how many numbers would appear if you counted from `l[0]` up to `l[n - 1]`, but are not present in the list.
+
+Example:
+
+Input:
+l = [1, 3, 4, 5, 7]
+
+Numbers between 1 and 7 would be:
+1, 2, 3, 4, 5, 6, 7
+
+Missing numbers:
+2, 6
+
+Output:
+2
+
+## Documentation
+
+### Solution Idea
+
+This problem can be solved with a simple mathematical observation.
+
+If `x` is the starting number (`l[0]`) and `y` is the final number (`l[n - 1]`), then there are always `y - x + 1` total numbers when counting from `x` to `y`.
+
+Since the list already contains `n` of those numbers, the number of missing numbers is:
+
+`(y - x + 1) - n`
+
+### [Implementation](./solver.ts)
+
+(I don't need to explain that 🙃)
+
+---
+
+### Information's
+
+This problem comes from the newsletter [Sloth Bytes](https://slothbytes.beehiiv.com).
+[Post](https://slothbytes.beehiiv.com/p/ai-agents) from November 18, 2025.

Problems/One-Two-Skip-A-Few/solver.ts

@@ -0,0 +1,4 @@
+export default function howManyMissing(list: number[]): number {
+	if (list.length <= 0) return 0;
+	return list.at(-1)! - list.at(0)! - list.length + 1;
+}

README.md

@@ -8,9 +8,9 @@ This repository is about solving coding-problems. It contains famous (or not tha
 
 ## Problems
 
-Solved: **20 problems**
+Solved: **21 problems**
 
-🟢 Easy: 14  
+🟢 Easy: 15  
 🟠 Medium: 5  
 🔴 Hard: 1
 
@@ -36,6 +36,7 @@ Solved: **20 problems**
 | [Shortest Path Dijkstra](./Problems/Shortes-Path-Dijkstra/README.md)                    | 🟠 Medium  |
 | [Sleep Time](./Problems/Sleep-Time/README.md)                                           | 🟢 Easy    |
 | [Reach Exit](./Problems/Reach-Exit/README.md)                                           | 🟢 Easy    |
+| [One Two Skip a Few](./Problems/One-Two-Skip-A-Few/README.md)                           | 🟢 Easy    |
 
 <!-- PROBLEMS_END -->
 

package.json

@@ -1,35 +1,35 @@
 {
-  "name": "problem-solving",
-  "version": "CP-20",
-  "description": "This Package is all about solving coding problems",
-  "homepage": "https://github.com/Dennis-Bauer/Problem-Solving#readme",
-  "bugs": {
-    "url": "https://github.com/Dennis-Bauer/Problem-Solving/issues"
-  },
-  "repository": {
-    "type": "git",
-    "url": "git+https://github.com/Dennis-Bauer/Problem-Solving.git"
-  },
-  "license": "ISC",
-  "author": "Dennis Bauer",
-  "type": "commonjs",
-  "scripts": {
-    "test": "vitest run ./Problems",
-    "test:dev": "vitest ./Problems --reporter=verbose",
-    "test:file": "vitest",
-    "test:ci": "vitest --run --passWithNoTests --reporter=json > vitest-report.json",
-    "build": "tsc",
-    "normalize": "biome check --write --unsafe",
-    "prepare": "husky install"
-  },
-  "dependencies": {
-    "decimal.js": "^10.6.0",
-    "husky": "^9.1.7",
-    "typescript": "^5.9.2",
-    "vitest": "^3.2.4"
-  },
-  "devDependencies": {
-    "@biomejs/biome": "2.3.11",
-    "@types/node": "^24.3.0"
-  }
+	"name": "problem-solving",
+	"version": "CP-20",
+	"description": "This Package is all about solving coding problems",
+	"homepage": "https://github.com/Dennis-Bauer/Problem-Solving#readme",
+	"bugs": {
+		"url": "https://github.com/Dennis-Bauer/Problem-Solving/issues"
+	},
+	"repository": {
+		"type": "git",
+		"url": "git+https://github.com/Dennis-Bauer/Problem-Solving.git"
+	},
+	"license": "ISC",
+	"author": "Dennis Bauer",
+	"type": "commonjs",
+	"scripts": {
+		"test": "vitest run ./Problems",
+		"test:dev": "vitest ./Problems --reporter=verbose",
+		"test:file": "vitest",
+		"test:ci": "vitest --run --passWithNoTests --reporter=json > vitest-report.json",
+		"build": "tsc",
+		"normalize": "biome check --write --unsafe",
+		"prepare": "husky install"
+	},
+	"dependencies": {
+		"decimal.js": "^10.6.0",
+		"husky": "^9.1.7",
+		"typescript": "^5.9.2",
+		"vitest": "^3.2.4"
+	},
+	"devDependencies": {
+		"@biomejs/biome": "2.3.11",
+		"@types/node": "^24.3.0"
+	}
 }