Exercises on dicts (#161)

* new exercises on dict

* Apply suggestions from code review

Co-authored-by: Mathieu <[email protected]>

* modifications from review

* minor: Readme and positioned after traits

---------

Co-authored-by: Mathieu <[email protected]>
Co-authored-by: Shramee Srivastav <[email protected]>

exercises/dict/README.md

@@ -0,0 +1,6 @@
+# Dicts
+The Felt252Dict maps a felt252 to a value of the specified type.
+
+## Further information
+
+- [Dictionaries](https://cairo-book.github.io/ch03-02-dictionaries.html)

exercises/dict/dict1.cairo

@@ -0,0 +1,30 @@
+// dict1.cairo
+// The Felt252Dict maps a felt252 to a value of the specified type.
+// In this exercise, you will map a `felt252` key to a value of type `u32`.
+
+// Your task is to create a `Felt252Dict`  containing three elements of type `u32`.
+// The first element shoud map the key 'A' to the value 1, the second key 'B' to the value 2 
+// and the third shoud map 'bob' to the value 3.
+// Make me compile and pass the test!
+// Execute `starklings hint dict1` or use the `hint` watch subcommand for a hint.
+
+// I AM NOT DONE
+
+
+fn create_dictionary() -> Felt252Dict<u32> {
+    let mut dict: Felt252Dict<u32> = Default::default();
+    //TODO
+
+}
+
+
+// Don't change anything in the test
+#[test]
+#[available_gas(200000)]
+fn test_dict() {
+    let mut dict = create_dictionary();
+    assert(dict.get('A') == 1, 'First element is not 1');
+    assert(dict.get('B') == 2, 'Second element is not 2');
+    assert(dict.get('bob') == 3, 'Third element is not 3');
+}
+

exercises/dict/dict2.cairo

@@ -0,0 +1,47 @@
+// dict2.cairo
+// Dictionaries can be used to simulate dynamic array : the value they store can be accessed and modified.
+// Your task is to create a function that mutliplies the elements stored at the indexes 0 to n of a dictionary by 10
+// Make me compile and pass the test!
+// Execute `starklings hint dict2` or use the `hint` watch subcommand for a hint.
+
+// I AM NOT DONE
+
+
+
+fn multiply_element_by_10(ref dict: Felt252Dict<u32>, n: usize) {
+    //TODO : make a function that mutliplies the elements stored at the indexes 0 to n of a dictionary by 10
+
+
+}
+
+// Don't change anything in the test
+#[test]
+#[available_gas(2000000000)]
+fn test_3() {
+    let mut dict: Felt252Dict<u32> = Default::default();
+    dict.insert(0, 1);
+    dict.insert(1, 2);
+    dict.insert(2, 3);
+
+    multiply_element_by_10(ref dict, 3);
+
+    assert(dict.get(0) == 10, 'First element is not 10');
+    assert(dict.get(1) == 20, 'Second element is not 20');
+    assert(dict.get(2) == 30, 'Third element is not 30');
+}
+
+#[test]
+#[available_gas(200000000)]
+fn test_4() {
+    let mut dict: Felt252Dict<u32> = Default::default();
+    dict.insert(0, 1);
+    dict.insert(1, 2);
+    dict.insert(2, 5);
+    dict.insert(3, 10);
+
+    multiply_element_by_10(ref dict, 4);
+
+    assert(dict.get(2) == 50, 'First element is not 50');
+    assert(dict.get(3) == 100, 'First element is not 100');
+
+}

exercises/dict/dict3.cairo

@@ -0,0 +1,67 @@
+// dict3.cairo
+// Custom data structure using dicts
+// Using Felt252Dict in structs allow us to simulate mutable data structures
+// In this exercise we have a struct Team where a Felt252Dict maps the name of a player to its level and keeps track of
+// the number of player.
+// Using the methods set and get from the Felt252DictTrait, implement the required functions to interact with the team
+// Make me compile and pass the test!
+// Execute `starklings hint dict3` or use the `hint` watch subcommand for a hint.
+
+
+// I AM NOT DONE
+
+
+#[derive(Destruct)]
+struct Team {
+  level: Felt252Dict<usize>,
+  players_count: usize 
+}
+
+#[generate_trait]
+impl TeamImpl of TeamTrait {
+    fn new() -> Team {
+        //TODO : initialize empty team with 0 player
+    }
+
+    fn get_level(ref self: Team, name: felt252) -> usize {
+        //TODO 
+    }
+
+    fn add_player(ref self: Team, name: felt252, level: usize) -> () {
+        //TODO
+    }
+
+    fn level_up(ref self: Team, name: felt252) {
+        //TODO
+    }
+
+    fn players_count(self: @Team) -> usize {
+        //TODO
+    }
+}
+
+
+
+#[test]
+#[available_gas(200000)]
+fn test_add_player() {
+
+    let mut team = TeamTrait::new();
+    team.add_player('bob', 10);
+    team.add_player('alice', 20);
+
+    assert(team.players_count == 2, 'Wrong number of player');
+    assert(team.get_level('bob') == 10, 'Wrong level');
+    assert(team.get_level('alice') == 20, 'Wrong level');
+}
+
+#[test]
+#[available_gas(200000)]
+fn test_level_up() {
+
+    let mut team = TeamTrait::new();
+    team.add_player('bobby',10);
+    team.level_up('bobby');
+
+    assert(team.level.get('bobby') == 11, 'Wrong level');
+}

info.toml

@@ -380,7 +380,6 @@ Looking at the test functions will also help you understand more about the synta
 This section will help you understanding more about methods https://cairo-book.github.io/ch05-03-method-syntax.html
 """
 
-
 # MOVE SEMANTICS
 
 [[exercises]]
@@ -506,6 +505,37 @@ If you're having trouble updating the distance value in the `Fish` and `Dog` imp
 3. Reconstruct `self` with the updated variables (`self = MyStruct { ... }`) 
 """
 
+# DICT
+
+[[exercises]]
+name = "dict1"
+path = "exercises/dict/dict1.cairo"
+mode = "test"
+hint = """
+More info about the Felt252Dict type can be found in the following chapter :
+https://cairo-book.github.io/ch03-02-dictionaries.html
+"""
+
+
+[[exercises]]
+name = "dict2"
+path = "exercises/dict/dict2.cairo"
+mode = "test"
+hint = """
+More info about the Felt252Dict type can be found in the following chapter :
+https://cairo-book.github.io/ch03-02-dictionaries.html
+"""
+
+
+[[exercises]]
+name = "dict3"
+path = "exercises/dict/dict3.cairo"
+mode = "test"
+hint = """
+Example of custom data structures using dicts can be found in this chapter :
+https://cairo-book.github.io/ch03-03-custom-data-structures.html
+"""
+
 # MODULES
 
 [[exercises]]