Basic types of data structures. Implementation in Java.

1. Lists, Stacks, Queues, Trees, Hash Tables Basic Data Structures

5. What Is a List?

7. Static and Linked Lists

11. Using the ArrayList class

17. Primes[n..m] Live Demo

18. Union and Intersection of Lists – Example public static Integer[] union(Integer[] firstArr, Integer[] secondArr) { List<Integer> union = new ArrayList<Integer>(); for (Integer item : firstArr) { union.add(item); } for (Integer item : secondArr) { if (!union.contains(item)) { union.add(item); } } return union.toArray(new Integer[union.size()]); } //Example continues...

19. Union and Intersection of Lists – Example(2) public static Integer[] intersect(Integer[] firstArr, Integer[] secondArr) { List<Integer> intersect = new ArrayList<Integer>(); for (Integer item : firstArr) { if (Arrays.binarySearch(secondArr, item) >= 0) { intersect.add(item); } } return intersect.toArray( new Integer[intersect.size()]); }

20. Union and Intersection Live Demo

21. What is a Stack?

25. Using the Stack class

28. Examples Using the Stack class

30. Live Demo Using the Stack class

32. Matching Brackets – Solution with a Stack String expression = &quot;1 + (3 + 2 - (2+3) * 4 - ((3+1)*(4-2)))&quot;; Stack<Integer> stack = new Stack<Integer>(); for (int i = 0; i < expression.length(); i++) { char ch = expression.charAt(i); if (ch == '(') { stack.push(i); } else if (ch == ')') { int startIndex = (int) stack.pop(); String contents = expression.substring(startIndex, i + 1); System.out.println(contents); } }

33. Live Demo Matching Brackets

34. What is a Queue?

38. Using the LinkedList class

41. Examples Using the LinkedList class

43. Live Demo Using the LinkedList class

45. Sequence – Solution int n = 3; int p = 16; Queue<Integer> queue = new LinkedList<Integer>(); queue.offer(n); int index = 0; while (queue.size() > 0) { index++; int current = queue.poll(); if (current == p) { System.out.println(&quot;Index = &quot; + index); return; } queue.offer(current + 1); queue.offer(2 * current); }

46. Live Demo Sequence N, N+1, 2*N

47. Definition, Types of Trees What is Tree?

53. What is a Dictionary (Map)?

55. What is a Hash Table?

61. Using the Hash Map class

65. Examples Using the HashMap Class

66. Hashtable - Example Map<String, Integer> studentsMarks = new HashMap<String, Integer>(); studentsMarks.put(&quot;Ivan&quot;, 4); studentsMarks.put(&quot;Peter&quot;, 6); studentsMarks.put(&quot;Maria&quot;, 6); studentsMarks.put(&quot;George&quot;, 5); int peterMark = studentsMarks.get(&quot;Peter&quot;); studentsMarks.remove(&quot;Peter&quot;); System.out.println(&quot;Is Peter in the hash table: &quot; + studentsMarks.containsKey(&quot;Peter&quot;)); for (Map.Entry<String, Integer> studentMark : studentsMarks.entrySet()) { System.out.printf(&quot;%s --> %d%n&quot;, studentMark.getKey(), studentMark.getValue()); }

67. Live Demo Using the HashMap Class

68. Counting Words in a Text String s = &quot;Welcome to our Java course. In this &quot; + &quot;course you will learn how to write simple &quot; + &quot;programs in Java&quot;; String[] words = s.split(&quot;[ ,.]&quot;); Map<String, Integer> wordsCount = new HashMap<String, Integer>(); for (String word : words) if (!&quot;&quot;.equalsIgnoreCase(word)) { int count = 1; if (wordsCount.containsKey(word)) count += wordsCount.get(word); wordsCount.put(word, count); } for (String word : wordsCount.keySet()) System.out.printf(&quot;%s --> %d%n&quot;, word, wordsCount.get(word));

69. Live Demo Counting Words in a Text

71. Basic Data Structures Questions?