{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Control Structures & Iterables — Code Cards (Classroom Version)\n",
    "\n",
    "## Try me\n",
    "[![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/ffraile/computer_science_tutorials/blob/main/source/Introduction/exercises/Basic%20control%20structure%20cards%20notebook.ipynb)[![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/ffraile/computer_science_tutorials/main?labpath=source%2FIntroduction%2Fexercises%2FBasic%20control%20structure%20cards%20notebook.ipynb)\n",
    "\n",
    "## How to use\n",
    "- Each card below mirrors the A4 activity prompt. First try to complete the exercise by yourself, **predict** the output or **find the bug** before running.\n",
    "- Then run the code cell to verify, or run the **Fix** cell (when provided) to see a correct version.\n",
    "- Keep explanations short and schematic (what/why).\n",
    "### Rendering Gemini into an interactive AI tutor\n",
    "- If you need help, hints, or extra exercises from AI, use the following prompt to convert it into an AI-tutor\n",
    "\n",
    "```markdown\n",
    "You are a **coding tutor** for Python in Jupyter/Colab. Follow the **course motto** “do not give up learning.”\n",
    "\n",
    "### Role & Goals\n",
    "- Use **Socratic guidance** and **test-first thinking** to help me solve problems myself.\n",
    "- Help me read errors, reason about state, and make small, safe iterations.\n",
    "\n",
    "### Strict Rules\n",
    "1) **Do not** provide full working solutions or paste complete functions/programs.\n",
    "   - You may show **tiny illustrative fragments (≤3 lines)** or **pseudo-code with TODOs**, but not a drop-in answer.\n",
    "2) Prefer **questions over answers**; offer **one small next step** at a time.\n",
    "3) When debugging, explain **what the traceback says**, give **2–3 hypotheses**, and propose the **smallest diff** in *plain English* first.\n",
    "4) Encourage **TDD**: ask me to write/assert a test, predict, run, and report outputs.\n",
    "5) Keep responses concise (≈120–150 words) unless I ask for a deeper explanation or code review.\n",
    "6) Ask me to **run code and share results**; adapt based on the output.\n",
    "7) If I request the full solution, remind me of the rules and offer a **higher-tier hint** instead.\n",
    "8) When I finalize an exercise, reinforce learning lessons and suggest additional exercises\n",
    "\n",
    "### Interaction Loop (use this structure)\n",
    "- **Restate goal:** what I’m trying to accomplish in one line.\n",
    "- **Diagnose:** key assumption to check or error to interpret.\n",
    "- **Hint (tiered):**\n",
    "  - Tier 1: Conceptual nudge (no code).\n",
    "  - Tier 2: Directed hint (identify line/construct to change).\n",
    "  - Tier 3: Pseudo-code with TODOs or a **1–3 line** pattern (still not a full solution).\n",
    "- **Next action:** one concrete step for me to try now.\n",
    "- **Ask back:** what to run/paste (output, test result, or traceback).\n",
    "\n",
    "### When reviewing my code\n",
    "- Comment on **correctness, clarity, naming, and complexity (big-O)**.\n",
    "- Suggest **tests** I’m missing (boundaries, empty cases, error paths).\n",
    "\n",
    "### Safety & Ethics\n",
    "- No secrets or private data in prompts.\n",
    "- avoid library functions/APIs unless I ask.\n",
    "\n",
    "Stay in tutor mode for the whole session.\n",
    "```"
   ],
   "id": "de6aea45f9d94a80"
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": "## Basic control structures - If-else statements\n",
   "id": "876e3c44bd5fe2c1"
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Card IF-1 — Predict the output\n",
    "\n",
    "```python\n",
    "x = 20\n",
    "if x < 20:\n",
    "    msg = \"A\"\n",
    "elif x <= 20:\n",
    "    msg = \"B\"\n",
    "else:\n",
    "    msg = \"C\"\n",
    "print(msg)\n",
    "```\n",
    "**Question:** What is printed?"
   ],
   "id": "1a8fdba52a530f0f"
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Card IF-1 — run to check\n",
    "x = 20\n",
    "if x < 20:\n",
    "    msg = \"A\"\n",
    "elif x <= 20:\n",
    "    msg = \"B\"\n",
    "else:\n",
    "    msg = \"C\"\n",
    "print(msg)  # expected: B"
   ],
   "id": "f64745c08ce74548"
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Card IF-2 — Predict the output\n",
    "\n",
    "```python\n",
    "x = 19\n",
    "msg = \"X\"\n",
    "if x < 20:\n",
    "    msg = \"A\"\n",
    "if x < 19:\n",
    "    msg = \"B\"\n",
    "else:\n",
    "    msg = \"C\"\n",
    "print(msg)\n",
    "```\n",
    "**Question:** What is printed?"
   ],
   "id": "835ca9c9101a2233"
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Card IF-2 — run to check\n",
    "x = 19\n",
    "msg = \"X\"\n",
    "if x < 20:\n",
    "    msg = \"A\"\n",
    "if x < 19:\n",
    "    msg = \"B\"\n",
    "else:\n",
    "    msg = \"C\"\n",
    "print(msg)  # expected: C (else binds to second if)"
   ],
   "id": "ba2a1872e27dcfee"
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Card IF-3 — Predict the output\n",
    "\n",
    "```python\n",
    "temp = 22\n",
    "if temp > 20:\n",
    "    if temp < 25:\n",
    "        res = \"A\"\n",
    "else:\n",
    "    res = \"B\"\n",
    "print(res)\n",
    "```\n",
    "**Question:** What is printed?"
   ],
   "id": "ad38efddba7c69b"
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Card IF-3 — run to check\n",
    "temp = 22\n",
    "if temp > 20:\n",
    "    if temp < 25:\n",
    "        res = \"A\"\n",
    "else:\n",
    "    res = \"B\"\n",
    "print(res)  # expected: A (nested if is True; outer else is skipped entirely)"
   ],
   "id": "d6a26097a30c82df"
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Card IF-4 — Code Wizard (Optimize the branching)\n",
    "\n",
    "Original:\n",
    "```python\n",
    "temp = 22\n",
    "if temp > 20:\n",
    "    if temp < 25:\n",
    "        res = \"A\"\n",
    "else:\n",
    "    res = \"B\"\n",
    "print(res)\n",
    "```\n",
    "**Task:** Rewrite with a clear `if/elif/else` chain."
   ],
   "id": "527385e6057d3b6f"
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Card IF-4 — one possible optimization\n",
    "temp = 22\n",
    "if temp <= 20:\n",
    "    res = \"B\"\n",
    "elif temp < 25:\n",
    "    res = \"A\"\n",
    "else:\n",
    "    res = \"B\"\n",
    "print(res)  # clearer mutually-exclusive branches"
   ],
   "id": "b9fa88de31b139dc"
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Card IF-5 — Predict the output\n",
    "\n",
    "```python\n",
    "score = 90\n",
    "if score >= 80:\n",
    "    grade = \"A\"\n",
    "elif score >= 90:\n",
    "    grade = \"A+\"\n",
    "else:\n",
    "    grade = \"B\"\n",
    "print(grade)\n",
    "```\n",
    "**Question:** What is printed?"
   ],
   "id": "7895fc7cf1ff8d32"
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Card IF-5 — run to check\n",
    "score = 90\n",
    "if score >= 80:\n",
    "    grade = \"A\"\n",
    "elif score >= 90:\n",
    "    grade = \"A+\"\n",
    "else:\n",
    "    grade = \"B\"\n",
    "print(grade)  # expected: A (first true branch wins)"
   ],
   "id": "4de1ff3f3f0c4ab6"
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 2) while loops — Human Calculator & Code Detective"
   ],
   "id": "91837f5141ab491e"
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Card WH-1 — Code Detective (Find the bug)\n",
    "\n",
    "Buggy code (indentation error):\n",
    "```python\n",
    "i = 0\n",
    "while i < 5:\n",
    "  i += 1\n",
    "    print(i)\n",
    "  if i % 2 == 0:\n",
    "    continue\n",
    "```\n",
    "**Task:** Fix indentation so it runs and behaves as intended."
   ],
   "id": "e2210e2479a1e24c"
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Card WH-1 — Fixed version\n",
    "i = 0\n",
    "while i < 5:\n",
    "    i += 1\n",
    "        print(i)\n",
    "    if i % 2 == 0:\n",
    "        continue"
   ],
   "id": "519eee7cf723f69c"
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Card WH-2 — Predict the output\n",
    "\n",
    "```python\n",
    "i = 3\n",
    "while i > 0:\n",
    "    print(i, end=\"\")\n",
    "    i -= 1\n",
    "print(\"done\")\n",
    "```\n",
    "**Question:** What is printed?"
   ],
   "id": "ad2b1d606a96c900"
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Card WH-2 — run to check\n",
    "i = 3\n",
    "while i > 0:\n",
    "    print(i, end=\"\")\n",
    "    i -= 1\n",
    "print(\"done\")  # expected: 321done"
   ],
   "id": "50f94579a935c106"
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Card WH-3 — Human Calculator\n",
    "\n",
    "```python\n",
    "n = 0\n",
    "while True:\n",
    "    n += 1\n",
    "    if n == 3:\n",
    "        continue\n",
    "print(n)\n",
    "```\n",
    "**Question:** How many times does the loop run?"
   ],
   "id": "e954aae6aac64dc7"
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Card WH-4 — Predict the output\n",
    "\n",
    "```python\n",
    "i, s = 0, 0\n",
    "while i < 5:\n",
    "  i += 1\n",
    "  if i % 2 == 0:\n",
    "    continue\n",
    "  s += i\n",
    "print(s)\n",
    "```\n",
    "**Question:** What is printed?"
   ],
   "id": "71337b6e78da2827"
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Card WH-4 — run to check\n",
    "i, s = 0, 0\n",
    "while i < 5:\n",
    "    i += 1\n",
    "    if i % 2 == 0:\n",
    "        continue\n",
    "    s += i\n",
    "print(s)"
   ],
   "id": "463790749562facd"
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## 3) for loops — Human Calculator & Code Detective"
   ],
   "id": "20df6437cf22bc9c"
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Card FOR-1 — Predict the output\n",
    "\n",
    "```python\n",
    "names = [\"A\",\"B\"]\n",
    "for i, n in enumerate(names, start=1):\n",
    "    print(i, n)\n",
    "```\n",
    "**Question:** What is printed?"
   ],
   "id": "a3ba1526009df22a"
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Card FOR-1 — run to check\n",
    "names = [\"A\",\"B\"]\n",
    "for i, n in enumerate(names, start=1):\n",
    "    print(i, n)"
   ],
   "id": "5b06e53555337f9b"
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Card FOR-2 — Predict the output\n",
    "\n",
    "```python\n",
    "for x in [0,1,2]:\n",
    "    if x:\n",
    "        continue\n",
    "    print(x)\n",
    "```\n",
    "**Question:** What is printed?"
   ],
   "id": "6a20ce4c51d9dd55"
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Card FOR-2 — run to check\n",
    "for x in [0,1,2]:\n",
    "    if x:\n",
    "        continue\n",
    "    print(x)"
   ],
   "id": "72f372e139e7f2c6"
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Card FOR-3 — Predict the output\n",
    "\n",
    "```python\n",
    "for i in range(5):\n",
    "    print(2**i)\n",
    "```\n",
    "**Question:** What is printed?"
   ],
   "id": "ca542429412c08e4"
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Card FOR-3 — run to check\n",
    "for i in range(5):\n",
    "    print(2**i)"
   ],
   "id": "425726ee849d622"
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Card FOR-4 — Code Detective (Find the bug)\n",
    "\n",
    "Prompt comment:\n",
    "```python\n",
    "# print odd numbers from 1 to 5 [1, 3, 5]\n",
    "for i in range(5, 1, 1):\n",
    "    print(i)\n",
    "```\n",
    "**Task:** Fix the loop to match the comment."
   ],
   "id": "e34d86684d6a1020"
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "# Fix the loop to match the comment. Hint: check range arguments\n",
    "for i in range(5, 1, 1):\n",
    "    print(i)  # 1, 3, 5"
   ],
   "id": "cfc7d1c79ee73df5"
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "---\n",
    "**Notes**\n",
    "- `if/elif/else`: first true branch executes; `else` binds to the nearest unmatched `if`.\n",
    "- `while True` without `break` never terminates.\n",
    "- `continue` skips to the next iteration; `break` exits the loop.\n",
    "- `enumerate(iterable, start=1)` yields `(index, item)`.\n",
    "- `range(start, stop, step)`: `stop` is **exclusive**."
   ],
   "id": "f7e9c1e47c462db9"
  },
  {
   "metadata": {},
   "cell_type": "markdown",
   "source": [
    "## Extra exercises\n",
    "### Card EX-1 — Predict the output\n",
    "```python\n",
    "for i in range(3):\n",
    "    for j in range(2):\n",
    "        if i == j:\n",
    "            print(i, j)\n",
    "```\n",
    "**Question:** What is printed?\n"
   ],
   "id": "b81c1f30843a1b85"
  },
  {
   "metadata": {},
   "cell_type": "code",
   "outputs": [],
   "execution_count": null,
   "source": [
    "for i in range(3):\n",
    "    for j in range(2):\n",
    "        if i == j:\n",
    "            print(i, j)"
   ],
   "id": "d7b0604121a5c2a"
  },
  {
   "metadata": {},
   "cell_type": "markdown",
   "source": [
    "### Card EX-2 — Code Wizard (Optimize the loop)\n",
    "**Task:** Fix the code so that \"Done\" is printed when the loop completes, without unnecessary logic. Explain your changes.\n",
    "```python\n",
    "i = 0\n",
    "while i < 5:\n",
    "    print(i)\n",
    "    i += 1\n",
    "    if i == 5:\n",
    "        print(\"Done\")\n",
    "        break\n",
    "```\n"
   ],
   "id": "b853095ee4f00126"
  },
  {
   "metadata": {},
   "cell_type": "code",
   "outputs": [],
   "execution_count": null,
   "source": [
    "i = 0\n",
    "while i < 5:\n",
    "    print(i)\n",
    "    i += 1\n",
    "    if i == 5:\n",
    "        print(\"Done\")\n",
    "        break"
   ],
   "id": "5378f21da3abd521"
  },
  {
   "metadata": {},
   "cell_type": "markdown",
   "source": [
    "### Card EX-3 — Human Calculator (Predict the output)\n",
    "What is printed?\n",
    "```python\n",
    "s = 0\n",
    "for i in range(1, 6, 2):\n",
    "    if i % 2 == 0:\n",
    "        s += i\n",
    "    else:\n",
    "        s += i * 2\n",
    "print(s)\n",
    "```\n"
   ],
   "id": "aeb339a1a2eeec61"
  },
  {
   "metadata": {},
   "cell_type": "code",
   "source": [
    "s = 0\n",
    "for i in range(1, 6, 2):\n",
    "    if i % 2 == 0:\n",
    "        s += i\n",
    "    else:\n",
    "        s += i * 2\n",
    "print(s)"
   ],
   "id": "2738ed32298f6540",
   "outputs": [],
   "execution_count": null
  },
  {
   "metadata": {},
   "cell_type": "markdown",
   "source": [
    "## Card EX-4 — Human Calculator (Predict the output)\n",
    "What is printed?\n",
    "```python\n",
    "a = [1, 2, 3, 4, 5, 6, 7]\n",
    "print(a[::-2])\n",
    "```\n"
   ],
   "id": "e4df727252e02a4d"
  },
  {
   "metadata": {},
   "cell_type": "code",
   "outputs": [],
   "execution_count": null,
   "source": [
    "a = [1, 2, 3, 4, 5, 6, 7]\n",
    "print(a[::-2])"
   ],
   "id": "b893f6baa4a67571"
  },
  {
   "metadata": {},
   "cell_type": "markdown",
   "source": [
    "## Card EX-5 — Code Wizard (Fix slicing)\n",
    "**Task:** Fix the code to print [\"B\", \"o\", \"n\", \"e\"] using as much defaults as possible\n",
    "```python\n",
    "b = [\"B\", \"r\", \"o\", \"w\", \"n\", \"i\", \"e\"]\n",
    "print(b[1:7:2])\n",
    "```\n"
   ],
   "id": "830653c2dd43319c"
  },
  {
   "metadata": {
    "ExecuteTime": {
     "end_time": "2025-10-18T11:37:10.755027Z",
     "start_time": "2025-10-18T11:37:10.752822Z"
    }
   },
   "cell_type": "code",
   "source": [
    "b = [\"B\", \"r\", \"o\", \"w\", \"n\", \"i\", \"e\"]\n",
    "print(b[1:7:2])"
   ],
   "id": "2ca236214ac092d4",
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "['r', 'w', 'i']\n"
     ]
    }
   ],
   "execution_count": 5
  }
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