From 13b026046e890026ab1d08b89c4c7e21d34ae92c Mon Sep 17 00:00:00 2001
From: Nenad <xinef.it@gmail.com>
Date: Sat, 9 Aug 2025 14:56:44 +0200
Subject: [PATCH 1/7] add concept exercise: bakery-order-system

---
 config.json                                   | 13 ++-
 .../bakery-order-system/.docs/hints.md        | 28 +++++++
 .../bakery-order-system/.docs/instructions.md | 42 ++++++++++
 .../bakery-order-system/.docs/introduction.md | 66 +++++++++++++++
 .../bakery-order-system/.meta/config.json     | 20 +++++
 .../bakery-order-system/.meta/design.md       | 19 +++++
 .../bakery-order-system/.meta/exemplar.cairo  | 50 ++++++++++++
 .../concept/bakery-order-system/Scarb.toml    |  7 ++
 .../concept/bakery-order-system/src/lib.cairo | 30 +++++++
 .../tests/bakery_order_system.cairo           | 81 +++++++++++++++++++
 10 files changed, 355 insertions(+), 1 deletion(-)
 create mode 100644 exercises/concept/bakery-order-system/.docs/hints.md
 create mode 100644 exercises/concept/bakery-order-system/.docs/instructions.md
 create mode 100644 exercises/concept/bakery-order-system/.docs/introduction.md
 create mode 100644 exercises/concept/bakery-order-system/.meta/config.json
 create mode 100644 exercises/concept/bakery-order-system/.meta/design.md
 create mode 100644 exercises/concept/bakery-order-system/.meta/exemplar.cairo
 create mode 100644 exercises/concept/bakery-order-system/Scarb.toml
 create mode 100644 exercises/concept/bakery-order-system/src/lib.cairo
 create mode 100644 exercises/concept/bakery-order-system/tests/bakery_order_system.cairo

diff --git a/config.json b/config.json
index e9cd57ec..3168a713 100644
--- a/config.json
+++ b/config.json
@@ -92,7 +92,6 @@
         "name": "RPN Calculator",
         "uuid": "536d9f09-5910-4a26-93fd-2242667b0b87",
         "concepts": [
-          "control-flow",
           "enums"
         ],
         "prerequisites": [
@@ -100,6 +99,18 @@
         ],
         "status": "wip"
       },
+      {
+        "slug": "bakery-order-system",
+        "name": "Bakery Order System",
+        "uuid": "536d9f09-5910-4a26-93fd-2242667b0b87",
+        "concepts": [
+          "control-flow"
+        ],
+        "prerequisites": [
+          "match-basics"
+        ],
+        "status": "wip"
+      },
       {
         "slug": "welcome-to-tech-palace",
         "name": "Welcome To Tech Palace!",
diff --git a/exercises/concept/bakery-order-system/.docs/hints.md b/exercises/concept/bakery-order-system/.docs/hints.md
new file mode 100644
index 00000000..b9defecc
--- /dev/null
+++ b/exercises/concept/bakery-order-system/.docs/hints.md
@@ -0,0 +1,28 @@
+# Hints
+
+## General
+
+- [The Cairo Book - Control Flow][tcb-control-flow]
+- [The Cairo Book - Arrays][tcb-arrays]
+
+## 1. Calculate Order Total
+
+- Use `match` or `if`/`else if` to handle different pastry types
+- Multiply the price per pastry by the quantity
+- Each pastry type has a fixed price in coins
+
+## 2. Apply Volume Discounts
+
+- Use `if`/`else if` to check discount tiers from highest to lowest
+- Remember that discounts should be applied as integer division (rounded down)
+- 10% discount means multiply by 90 and divide by 100
+
+## 3. Create Baking Schedule
+
+- Use a `loop` to build the schedule hour by hour
+- Each hour, bake up to 5 orders (or whatever remains)
+- Continue until all orders are scheduled
+- Use `break` when no more orders remain
+
+[tcb-control-flow]: https://www.starknet.io/cairo-book/ch02-05-control-flow.html
+[tcb-arrays]: https://www.starknet.io/cairo-book/ch03-01-arrays.html
diff --git a/exercises/concept/bakery-order-system/.docs/instructions.md b/exercises/concept/bakery-order-system/.docs/instructions.md
new file mode 100644
index 00000000..6907af0c
--- /dev/null
+++ b/exercises/concept/bakery-order-system/.docs/instructions.md
@@ -0,0 +1,42 @@
+# Instructions
+
+In this exercise you'll help manage a small bakery's daily operations using Cairo's control flow constructs.
+
+## 1. Calculate Order Total
+
+Implement `calculate_total` that calculates the cost of an order based on pastry type and quantity:
+
+- Croissant: 3 coins each
+- Muffin: 2 coins each  
+- Cookie: 1 coin each
+
+```rust
+calculate_total(Pastry::Croissant, 4) // Returns: 12 (4 * 3)
+calculate_total(Pastry::Cookie, 10)   // Returns: 10 (10 * 1)
+```
+
+## 2. Apply Volume Discounts
+
+Implement `apply_discount` that applies discounts based on order total:
+
+- Orders ≥ 20 coins: 10% discount
+- Orders ≥ 10 coins: 5% discount
+- Orders < 10 coins: no discount
+
+```rust
+apply_discount(25) // Returns: 22 (25 - 10% = 22.5, rounded down)
+apply_discount(15) // Returns: 14 (15 - 5% = 14.25, rounded down)
+apply_discount(8)  // Returns: 8 (no discount)
+```
+
+## 3. Create Baking Schedule
+
+Implement `baking_schedule` that creates a daily baking plan. The bakery bakes in batches of 5 orders per hour:
+
+```rust
+baking_schedule(18) // Returns: [5, 5, 5, 3] (3 full batches + 3 remaining)
+baking_schedule(10) // Returns: [5, 5] (2 full batches)
+baking_schedule(3)  // Returns: [3] (1 partial batch)
+```
+
+Use appropriate control flow constructs (`if`/`else`, `loop`) to solve each problem efficiently.
diff --git a/exercises/concept/bakery-order-system/.docs/introduction.md b/exercises/concept/bakery-order-system/.docs/introduction.md
new file mode 100644
index 00000000..81eb4091
--- /dev/null
+++ b/exercises/concept/bakery-order-system/.docs/introduction.md
@@ -0,0 +1,66 @@
+# Introduction
+
+Control flow in Cairo allows you to control the execution path of your programs based on conditions and repetition.
+
+## Conditional Execution
+
+Use `if` expressions to execute code based on conditions:
+
+```rust
+let number = 42;
+if number > 0 {
+    println!("Positive number");
+} else if number < 0 {
+    println!("Negative number");  
+} else {
+    println!("Zero");
+}
+```
+
+`if` is an expression, so it can return values:
+
+```rust
+let result = if condition { 5 } else { 10 };
+```
+
+## Loops
+
+Use `loop` to repeat code until a condition is met:
+
+```rust
+let mut counter = 0;
+loop {
+    if counter == 5 {
+        break;
+    }
+    println!("Counter: {}", counter);
+    counter += 1;
+}
+```
+
+Loops can return values using `break`:
+
+```rust
+let result = loop {
+    counter += 1;
+    if counter == 10 {
+        break counter * 2; // Returns 20
+    }
+};
+```
+
+Use `continue` to skip to the next iteration:
+
+```rust
+let mut i = 0;
+loop {
+    i += 1;
+    if i % 2 == 0 {
+        continue; // Skip even numbers
+    }
+    if i > 10 {
+        break;
+    }
+    println!("{}", i); // Only prints odd numbers
+}
+```
diff --git a/exercises/concept/bakery-order-system/.meta/config.json b/exercises/concept/bakery-order-system/.meta/config.json
new file mode 100644
index 00000000..ff7890e7
--- /dev/null
+++ b/exercises/concept/bakery-order-system/.meta/config.json
@@ -0,0 +1,20 @@
+{
+  "authors": [
+    "0xNeshi"
+  ],
+  "files": {
+    "solution": [
+      "src/lib.cairo"
+    ],
+    "test": [
+      "tests/bakery_order_system.cairo"
+    ],
+    "example": [
+      ".meta/example.cairo"
+    ],
+    "invalidator": [
+      "Scarb.toml"
+    ]
+  },
+  "blurb": "Learn Cairo's control flow constructs while managing a bakery's daily operations."
+}
\ No newline at end of file
diff --git a/exercises/concept/bakery-order-system/.meta/design.md b/exercises/concept/bakery-order-system/.meta/design.md
new file mode 100644
index 00000000..d14ef88b
--- /dev/null
+++ b/exercises/concept/bakery-order-system/.meta/design.md
@@ -0,0 +1,19 @@
+# Design
+
+## Learning Objectives
+
+- Know how to use control flow constructs.
+
+## Concepts
+
+- Control flow
+
+## Prerequisites
+
+- Match basics
+
+## Resources to Refer To
+
+- [Cairo Book - Control Flow][cf]
+
+[cf]: https://www.starknet.io/cairo-book/ch02-05-control-flow.html
diff --git a/exercises/concept/bakery-order-system/.meta/exemplar.cairo b/exercises/concept/bakery-order-system/.meta/exemplar.cairo
new file mode 100644
index 00000000..0109fc9d
--- /dev/null
+++ b/exercises/concept/bakery-order-system/.meta/exemplar.cairo
@@ -0,0 +1,50 @@
+#[derive(Drop, PartialEq)]
+pub enum Pastry {
+    Croissant,
+    Muffin,
+    Cookie,
+}
+
+pub fn calculate_total(pastry: Pastry, quantity: u32) -> u32 {
+    let price_per_item = match pastry {
+        Pastry::Croissant => 3,
+        Pastry::Muffin => 2,
+        Pastry::Cookie => 1,
+    };
+
+    price_per_item * quantity
+}
+
+pub fn apply_discount(total: u32) -> u32 {
+    if total >= 20 {
+        // 10% discount: multiply by 90, divide by 100
+        (total * 90) / 100
+    } else if total >= 10 {
+        // 5% discount: multiply by 95, divide by 100
+        (total * 95) / 100
+    } else {
+        // No discount
+        total
+    }
+}
+
+pub fn baking_schedule(total_orders: u32) -> Array<u32> {
+    let mut schedule = ArrayTrait::new();
+    let mut remaining_orders = total_orders;
+
+    loop {
+        if remaining_orders == 0 {
+            break;
+        }
+
+        if remaining_orders >= 5 {
+            schedule.append(5);
+            remaining_orders -= 5;
+        } else {
+            schedule.append(remaining_orders);
+            remaining_orders = 0;
+        }
+    }
+
+    schedule
+}
diff --git a/exercises/concept/bakery-order-system/Scarb.toml b/exercises/concept/bakery-order-system/Scarb.toml
new file mode 100644
index 00000000..e5ec1ddf
--- /dev/null
+++ b/exercises/concept/bakery-order-system/Scarb.toml
@@ -0,0 +1,7 @@
+[package]
+name = "bakery_order_system"
+version = "0.1.0"
+edition = "2024_07"
+
+[dev-dependencies]
+cairo_test = "2.9.2"
diff --git a/exercises/concept/bakery-order-system/src/lib.cairo b/exercises/concept/bakery-order-system/src/lib.cairo
new file mode 100644
index 00000000..9d32699c
--- /dev/null
+++ b/exercises/concept/bakery-order-system/src/lib.cairo
@@ -0,0 +1,30 @@
+/// Types of pastries available in the bakery
+#[derive(Drop, PartialEq)]
+pub enum Pastry {
+    Croissant,
+    Muffin,
+    Cookie,
+}
+
+/// Calculate the total cost of an order
+pub fn calculate_total(pastry: Pastry, quantity: u32) -> u32 {
+    // Croissant: 3 coins, Muffin: 2 coins, Cookie: 1 coin
+    // Return total cost for the given quantity
+    panic!("implement `calculate_total`")
+}
+
+/// Apply discount based on order size
+pub fn apply_discount(total: u32) -> u32 {
+    // Orders >= 20 coins: 10% discount
+    // Orders >= 10 coins: 5% discount
+    // Orders < 10 coins: no discount
+    panic!("implement `apply_discount`")
+}
+
+/// Generate the daily baking schedule
+pub fn baking_schedule(total_orders: u32) -> Array<u32> {
+    // Bake in batches of 5 orders each
+    // Return an array showing how many orders are baked each hour
+    // Continue until all orders are completed
+    panic!("implement `baking_schedule`")
+}
diff --git a/exercises/concept/bakery-order-system/tests/bakery_order_system.cairo b/exercises/concept/bakery-order-system/tests/bakery_order_system.cairo
new file mode 100644
index 00000000..128189b3
--- /dev/null
+++ b/exercises/concept/bakery-order-system/tests/bakery_order_system.cairo
@@ -0,0 +1,81 @@
+use bakery_order_system::{Pastry, calculate_total, apply_discount, baking_schedule};
+
+#[test]
+fn test_calculate_croissant_total() {
+    assert_eq!(calculate_total(Pastry::Croissant, 4), 12);
+    assert_eq!(calculate_total(Pastry::Croissant, 1), 3);
+}
+
+#[test]
+#[ignore]
+fn test_calculate_muffin_total() {
+    assert_eq!(calculate_total(Pastry::Muffin, 5), 10);
+    assert_eq!(calculate_total(Pastry::Muffin, 3), 6);
+}
+
+#[test]
+#[ignore]
+fn test_calculate_cookie_total() {
+    assert_eq!(calculate_total(Pastry::Cookie, 10), 10);
+    assert_eq!(calculate_total(Pastry::Cookie, 7), 7);
+}
+
+#[test]
+#[ignore]
+fn test_no_discount() {
+    assert_eq!(apply_discount(5), 5);
+    assert_eq!(apply_discount(9), 9);
+}
+
+#[test]
+#[ignore]
+fn test_five_percent_discount() {
+    assert_eq!(apply_discount(10), 9); // 10 * 0.95 = 9.5, rounded down to 9
+    assert_eq!(apply_discount(15), 14); // 15 * 0.95 = 14.25, rounded down to 14
+    assert_eq!(apply_discount(19), 18); // 19 * 0.95 = 18.05, rounded down to 18
+}
+
+#[test]
+#[ignore]
+fn test_ten_percent_discount() {
+    assert_eq!(apply_discount(20), 18); // 20 * 0.9 = 18
+    assert_eq!(apply_discount(25), 22); // 25 * 0.9 = 22.5, rounded down to 22
+    assert_eq!(apply_discount(30), 27); // 30 * 0.9 = 27
+}
+
+#[test]
+#[ignore]
+fn test_baking_schedule_multiple_batches() {
+    let result = baking_schedule(18);
+    let expected = [5, 5, 5, 3].span();
+
+    assert_eq!(result.len(), 4);
+    assert_eq!(result.span(), expected);
+}
+
+#[test]
+#[ignore]
+fn test_baking_schedule_exact_batches() {
+    let result = baking_schedule(10);
+    let expected = [5, 5].span();
+
+    assert_eq!(result.len(), 2);
+    assert_eq!(result.span(), expected);
+}
+
+#[test]
+#[ignore]
+fn test_baking_schedule_single_partial_batch() {
+    let result = baking_schedule(3);
+    let expected = [3].span();
+
+    assert_eq!(result.len(), 1);
+    assert_eq!(result.span(), expected);
+}
+
+#[test]
+#[ignore]
+fn test_baking_schedule_zero_orders() {
+    let result = baking_schedule(0);
+    assert_eq!(result.len(), 0);
+}

From ea39920eb3f8fc905c35f481aef9153f3f072cdc Mon Sep 17 00:00:00 2001
From: Nenad <xinef.it@gmail.com>
Date: Sat, 9 Aug 2025 14:58:05 +0200
Subject: [PATCH 2/7] fmt

---
 exercises/concept/bakery-order-system/.docs/instructions.md | 3 ++-
 exercises/concept/bakery-order-system/.meta/config.json     | 6 +++---
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/exercises/concept/bakery-order-system/.docs/instructions.md b/exercises/concept/bakery-order-system/.docs/instructions.md
index 6907af0c..1efbbdaf 100644
--- a/exercises/concept/bakery-order-system/.docs/instructions.md
+++ b/exercises/concept/bakery-order-system/.docs/instructions.md
@@ -31,7 +31,8 @@ apply_discount(8)  // Returns: 8 (no discount)
 
 ## 3. Create Baking Schedule
 
-Implement `baking_schedule` that creates a daily baking plan. The bakery bakes in batches of 5 orders per hour:
+Implement `baking_schedule` that creates a daily baking plan.
+The bakery bakes in batches of 5 orders per hour:
 
 ```rust
 baking_schedule(18) // Returns: [5, 5, 5, 3] (3 full batches + 3 remaining)
diff --git a/exercises/concept/bakery-order-system/.meta/config.json b/exercises/concept/bakery-order-system/.meta/config.json
index ff7890e7..d7f7583f 100644
--- a/exercises/concept/bakery-order-system/.meta/config.json
+++ b/exercises/concept/bakery-order-system/.meta/config.json
@@ -9,12 +9,12 @@
     "test": [
       "tests/bakery_order_system.cairo"
     ],
-    "example": [
-      ".meta/example.cairo"
+    "exemplar": [
+      ".meta/exemplar.cairo"
     ],
     "invalidator": [
       "Scarb.toml"
     ]
   },
   "blurb": "Learn Cairo's control flow constructs while managing a bakery's daily operations."
-}
\ No newline at end of file
+}

From 31c8fc52f6bce2c46d6122c555e64f6b4115e0ef Mon Sep 17 00:00:00 2001
From: Nenad <xinef.it@gmail.com>
Date: Sat, 9 Aug 2025 15:00:17 +0200
Subject: [PATCH 3/7] fix config uuid

---
 config.json | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/config.json b/config.json
index 3168a713..134c3455 100644
--- a/config.json
+++ b/config.json
@@ -102,7 +102,7 @@
       {
         "slug": "bakery-order-system",
         "name": "Bakery Order System",
-        "uuid": "536d9f09-5910-4a26-93fd-2242667b0b87",
+        "uuid": "a979b9a0-7fd9-46f7-bacf-f0044c3c9bb0",
         "concepts": [
           "control-flow"
         ],

From c030aaf08aa0cac67e3241e1b2071b6743e4856b Mon Sep 17 00:00:00 2001
From: Nenad <xinef.it@gmail.com>
Date: Sat, 9 Aug 2025 15:01:22 +0200
Subject: [PATCH 4/7] add missing semicolon

---
 exercises/concept/bakery-order-system/.meta/exemplar.cairo | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/exercises/concept/bakery-order-system/.meta/exemplar.cairo b/exercises/concept/bakery-order-system/.meta/exemplar.cairo
index 0109fc9d..221a3b51 100644
--- a/exercises/concept/bakery-order-system/.meta/exemplar.cairo
+++ b/exercises/concept/bakery-order-system/.meta/exemplar.cairo
@@ -44,7 +44,7 @@ pub fn baking_schedule(total_orders: u32) -> Array<u32> {
             schedule.append(remaining_orders);
             remaining_orders = 0;
         }
-    }
+    };
 
     schedule
 }

From c2864fab4d6196d113f837df0f17c97632b802b4 Mon Sep 17 00:00:00 2001
From: Nenad <xinef.it@gmail.com>
Date: Sun, 10 Aug 2025 10:33:19 +0200
Subject: [PATCH 5/7] wip -> beta

---
 config.json | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/config.json b/config.json
index 134c3455..9e2a089c 100644
--- a/config.json
+++ b/config.json
@@ -109,7 +109,7 @@
         "prerequisites": [
           "match-basics"
         ],
-        "status": "wip"
+        "status": "beta"
       },
       {
         "slug": "welcome-to-tech-palace",

From 9127bec9f46658a90d68495045066bcf2c06e264 Mon Sep 17 00:00:00 2001
From: 0xNeshi <nenad.misic@openzeppelin.com>
Date: Sun, 17 Aug 2025 15:53:23 +0200
Subject: [PATCH 6/7] introduce break earlier

---
 exercises/concept/bakery-order-system/.docs/introduction.md | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/exercises/concept/bakery-order-system/.docs/introduction.md b/exercises/concept/bakery-order-system/.docs/introduction.md
index 81eb4091..08a141eb 100644
--- a/exercises/concept/bakery-order-system/.docs/introduction.md
+++ b/exercises/concept/bakery-order-system/.docs/introduction.md
@@ -25,7 +25,8 @@ let result = if condition { 5 } else { 10 };
 
 ## Loops
 
-Use `loop` to repeat code until a condition is met:
+Use `loop` to repeat code.
+A loop runs indefinitely unless you stop it; use `break` to exit the loop when a condition is met.
 
 ```rust
 let mut counter = 0;

From b2ebd53a867e58e58f9dcc4efab44e91e57d26ba Mon Sep 17 00:00:00 2001
From: 0xNeshi <nenad.misic@openzeppelin.com>
Date: Sun, 17 Aug 2025 15:55:40 +0200
Subject: [PATCH 7/7] introduce round down earlier

---
 .../concept/bakery-order-system/.docs/instructions.md    | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/exercises/concept/bakery-order-system/.docs/instructions.md b/exercises/concept/bakery-order-system/.docs/instructions.md
index 1efbbdaf..920a24c3 100644
--- a/exercises/concept/bakery-order-system/.docs/instructions.md
+++ b/exercises/concept/bakery-order-system/.docs/instructions.md
@@ -17,16 +17,17 @@ calculate_total(Pastry::Cookie, 10)   // Returns: 10 (10 * 1)
 
 ## 2. Apply Volume Discounts
 
-Implement `apply_discount` that applies discounts based on order total:
+Implement `apply_discount` that applies discounts based on order total.
+Apply the percentage discount to the total, then round down to the nearest whole coin (floor).
 
 - Orders ≥ 20 coins: 10% discount
 - Orders ≥ 10 coins: 5% discount
 - Orders < 10 coins: no discount
 
 ```rust
-apply_discount(25) // Returns: 22 (25 - 10% = 22.5, rounded down)
-apply_discount(15) // Returns: 14 (15 - 5% = 14.25, rounded down)
-apply_discount(8)  // Returns: 8 (no discount)
+apply_discount(25) // Returns: 22
+apply_discount(15) // Returns: 14
+apply_discount(8)  // Returns: 8
 ```
 
 ## 3. Create Baking Schedule