added resources, coding challenges, and more study guides

2024-10-05 16:05:26 -05:00
parent d159c2ae51
commit a35b6e5ef4
17 changed files with 1875 additions and 1 deletions
@@ -0,0 +1,160 @@
+# Dart Collections: A Comprehensive Guide
+
+Dart provides several built-in collection types to help you manage and manipulate groups of objects. This guide covers the main collection types and their operations.
+
+## 1. Lists
+
+Lists are ordered, indexable collections of objects.
+
+### Example:
+
+```dart
+void main() {
+  // Creating lists
+  var numbers = [1, 2, 3, 4, 5];
+  List<String> fruits = ['apple', 'banana', 'orange'];
+
+  // Accessing elements
+  print(numbers[0]); // 1
+  print(fruits.last); // orange
+
+  // Adding elements
+  numbers.add(6);
+  fruits.addAll(['grape', 'mango']);
+
+  // Removing elements
+  numbers.remove(3);
+  fruits.removeAt(0);
+
+  // Other operations
+  print(numbers.length); // 5
+  print(fruits.contains('banana')); // true
+  
+  // Iterating
+  for (var fruit in fruits) {
+    print(fruit);
+  }
+
+  // Functional operations
+  var doubledNumbers = numbers.map((n) => n * 2).toList();
+  var evenNumbers = numbers.where((n) => n.isEven).toList();
+}
+```
+
+## 2. Sets
+
+Sets are unordered collections of unique items.
+
+### Example:
+
+```dart
+void main() {
+  // Creating sets
+  var uniqueNumbers = {1, 2, 3, 4, 5};
+  Set<String> uniqueFruits = {'apple', 'banana', 'orange'};
+
+  // Adding elements
+  uniqueNumbers.add(6);
+  uniqueFruits.addAll(['grape', 'mango']);
+
+  // Removing elements
+  uniqueNumbers.remove(3);
+
+  // Set operations
+  var setA = {1, 2, 3, 4};
+  var setB = {3, 4, 5, 6};
+  print(setA.union(setB)); // {1, 2, 3, 4, 5, 6}
+  print(setA.intersection(setB)); // {3, 4}
+  print(setA.difference(setB)); // {1, 2}
+
+  // Checking membership
+  print(uniqueFruits.contains('banana')); // true
+
+  // Iterating
+  for (var number in uniqueNumbers) {
+    print(number);
+  }
+}
+```
+
+## 3. Maps
+
+Maps are collections of key-value pairs.
+
+### Example:
+
+```dart
+void main() {
+  // Creating maps
+  var ages = {'Alice': 30, 'Bob': 25, 'Charlie': 35};
+  Map<String, int> scores = {'Math': 90, 'Science': 85, 'History': 95};
+
+  // Accessing values
+  print(ages['Alice']); // 30
+  print(scores['Math']); // 90
+
+  // Adding or updating entries
+  ages['David'] = 28;
+  scores.addAll({'Geography': 88, 'Literature': 92});
+
+  // Removing entries
+  ages.remove('Bob');
+
+  // Checking keys and values
+  print(ages.containsKey('Charlie')); // true
+  print(scores.containsValue(100)); // false
+
+  // Iterating
+  ages.forEach((key, value) {
+    print('$key is $value years old');
+  });
+
+  // Getting all keys or values
+  print(scores.keys);
+  print(scores.values);
+}
+```
+
+## 4. Collection Methods and Operations
+
+Dart provides many useful methods for working with collections.
+
+### Example:
+
+```dart
+void main() {
+  var numbers = [1, 2, 3, 4, 5];
+
+  // Functional methods
+  var doubled = numbers.map((n) => n * 2);
+  var evenNumbers = numbers.where((n) => n.isEven);
+  var sum = numbers.reduce((a, b) => a + b);
+  var product = numbers.fold(1, (a, b) => a * b);
+
+  print(doubled); // (2, 4, 6, 8, 10)
+  print(evenNumbers); // (2, 4)
+  print(sum); // 15
+  print(product); // 120
+
+  // Sorting
+  var fruits = ['banana', 'apple', 'orange'];
+  fruits.sort();
+  print(fruits); // [apple, banana, orange]
+
+  // Reversing
+  var reversedNumbers = numbers.reversed;
+  print(reversedNumbers); // (5, 4, 3, 2, 1)
+
+  // Shuffling
+  numbers.shuffle();
+  print(numbers); // Random order
+
+  // Finding elements
+  var firstEven = numbers.firstWhere((n) => n.isEven, orElse: () => -1);
+  print(firstEven);
+}
+```
+
+## Conclusion
+
+Dart's collection types provide powerful tools for managing groups of objects. Understanding how to effectively use Lists, Sets, and Maps, along with their associated methods and operations, is crucial for efficient Dart programming.