1. Chemistry CS1020

2.  Given a set of mappings and chemical formula: Calculate the molecule mass of the formula Problem Description C12 H1 N14 O16 (NH 4 ) 2 CO 3

3.  Let’s work on a few examples based on the given mapping Problem Description C12 H1 N14 O16 (NH 4 ) 2 CO 3 ((CH 3 )CH 4 C 3 H 8 ) 4 CH 4 OH

4.  Let’s work on a few examples based on the given mapping Problem Description C12 H1 N14 O16 (NH 4 ) 2 CO 3 ((CH 3 )CH 4 C 3 H 8 ) 4 CH 4 OH 14 + 4 x 1

5.  Let’s work on a few examples based on the given mapping Problem Description C12 H1 N14 O16 (NH 4 ) 2 CO 3 ((CH 3 )CH 4 C 3 H 8 ) 4 CH 4 OH 18 * 2

6.  Let’s work on a few examples based on the given mapping Problem Description C12 H1 N14 O16 36 + CO 3 ((CH 3 )CH 4 C 3 H 8 ) 4 CH 4 OH 12 + 3 x 16

7.  Let’s work on a few examples based on the given mapping Problem Description C12 H1 N14 O16 36 + CO 3 ((CH 3 )CH 4 C 3 H 8 ) 4 CH 4 OH 60

8.  Let’s work on a few examples based on the given mapping Problem Description C12 H1 N14 O16 36 + 60 ((CH 3 )CH 4 C 3 H 8 ) 4 CH 4 OH

9.  Let’s work on a few examples based on the given mapping Problem Description C12 H1 N14 O16 (NH 4 ) 2 CO 3 ((CH 3 )CH 4 C 3 H 8 ) 4 CH 4 OH M r = 96

10.  Let’s work on a few examples based on the given mapping Problem Description C12 H1 N14 O16 (NH 4 ) 2 CO 3 ((CH 3 )CH 4 C 3 H 8 ) 4 CH 4 OH M r = 96 12 + 4 x 1 + 16 + 1

11.  Let’s work on a few examples based on the given mapping Problem Description C12 H1 N14 O16 (NH 4 ) 2 CO 3 ((CH 3 )CH 4 C 3 H 8 ) 4 CH 4 OH M r = 96 33

12.  Let’s work on a few examples based on the given mapping Problem Description C12 H1 N14 O16 (NH 4 ) 2 CO 3 ((CH 3 )CH 4 C 3 H 8 ) 4 CH 4 OH M r = 96 M r = 33

13.  Let’s work on a few examples based on the given mapping C12 H1 N14 O16 (NH 4 ) 2 CO 3 ((CH 3 )CH 4 C 3 H 8 ) 4 CH 4 OH M r = 96 M r = 33 12 + 3 x 1

14.  Let’s work on a few examples based on the given mapping C12 H1 N14 O16 (NH 4 ) 2 CO 3 ((CH 3 )CH 4 C 3 H 8 ) 4 CH 4 OH M r = 96 M r = 33 15

15.  Let’s work on a few examples based on the given mapping C12 H1 N14 O16 (NH 4 ) 2 CO 3 (15 + CH 4 C 3 H 8 ) 4 CH 4 OH M r = 96 M r = 33 12 + 4 x 1 + 3 x 12 + 8 x 1

16.  Let’s work on a few examples based on the given mapping C12 H1 N14 O16 (NH 4 ) 2 CO 3 (15 + CH 4 C 3 H 8 ) 4 CH 4 OH M r = 96 M r = 33 60

17.  Let’s work on a few examples based on the given mapping C12 H1 N14 O16 (NH 4 ) 2 CO 3 (15 + 60) 4 CH 4 OH M r = 96 M r = 33

18.  Let’s work on a few examples based on the given mapping Problem Description C12 H1 N14 O16 (NH 4 ) 2 CO 3 ((CH 3 )CH 4 C 3 H 8 ) 4 CH 4 OH M r = 96 M r = 33 M r = 300

19. ? What data structure should I use for: Mass Mapping HashMap Formula Processing Stack

20. HashMap https://docs.oracle.com/javase/8/docs/api/java/util/HashMap.html HashMap hashMapName = new HashMap (); HashMap massMapping = new HashMap (); massMapping.put(‘C’, 12); massMapping.put(‘H’, 1); massMapping.put(‘N’, 14); massMapping.get(‘C’); massMapping.get(‘H’); massMapping.get(‘N’); Setting Keys and ValuesRetrieving Values Returns 12 Returns 1 Returns 14

21. https://docs.oracle.com/javase/8/docs/api/java/util/Stack.html Stack What should my stack contain? Mass of each AtomThe Elements OR

22. https://docs.oracle.com/javase/8/docs/api/java/util/Stack.html Stack What should my stack contain? Mass of each AtomThe Elements We will use a stack of integers CH 4 Stack

23. https://docs.oracle.com/javase/8/docs/api/java/util/Stack.html Stack What should my stack contain? Mass of each AtomThe Elements We will use a stack of integers CH4CH4 Stack 12

24. https://docs.oracle.com/javase/8/docs/api/java/util/Stack.html Stack What should my stack contain? Mass of each AtomThe Elements We will use a stack of integers CH4CH4 Stack 12 1

25. https://docs.oracle.com/javase/8/docs/api/java/util/Stack.html Stack What should my stack contain? Mass of each AtomThe Elements We will use a stack of integers CH 4 Stack 12 14

26. https://docs.oracle.com/javase/8/docs/api/java/util/Stack.html Stack What should my stack contain? Mass of each AtomThe Elements We will use a stack of integers CH 4 Stack 12 14 Total = 12 + 4 = 16

27. How do I store the formula? ? As a character array String nextLine = sc.nextLine(); char[] formula = nextLine.toCharArray(); How do I process the formula? Loop through all characters processInput(formula);

28. public void run() { Scanner sc = new Scanner(System.in); int n = sc.nextInt(); sc.nextLine(); initializeMassMapping(sc, n); //implement it String nextLine = sc.nextLine(); char[] formula = nextLine.toCharArray(); processInput(formula); int total = accumulate(); //will be defined later System.out.println(total); sc.close(); }

29. private void processInput(char[] formula) { for (char c : formula) { //what should I do??? } Next character can be one of these: ( ) X n Open Bracket Close Bracket Atom Name Number of atoms (or molecules) What you should do if you encounter it: Start New “Session” Acummulate Current “Session” Push Its Mass Multiply Top of The Stack by n

30. private void processInput(char[] formula) { for (char c : formula) { if (c == '(') { //open bracket results.push(-1); //start a new “session” } else if (c == ')') { //close bracket int sum = accumulate(); //acummulate is a “helper” //then push the sum into the stack } else if (Character.isDigit(c)) {//it’s a number //multiply the top of the stack. How? } else { //then c must be a ??? //push the corresponding atom’s mass } } }

31. private int accumulate() { int result = 0; int top = results.pop(); while (/* top is not -1 and stack is not empty */) { //add current top to result //update top to be next element in stack } return result; }

32. Visualization CH 4 Stack

33. Visualization CH4CH4 Stack 12 Push The Mass of ‘C’ Into The Stack

34. Visualization CH4CH4 Stack 12 Push The Mass of ‘H’ Into The Stack 1

35. Visualization CH 4 Stack 12 Multiply top of stack by 4 1

36. Visualization CH 4 Stack 12 Multiply top of stack by 4 4

37. Visualization CH 4 Stack 12 Accumulate all values 4 4 + 12 = 16

38. Visualization N(CH 2 (CH 3 ) 2 ) 3 Stack

39. Visualization N(CH 2 (CH 3 ) 2 ) 3 Stack Push The Mass of ‘N’ Into The Stack 14

40. Visualization N(CH 2 (CH 3 ) 2 ) 3 Stack Start New Session 14

41. Visualization N(CH 2 (CH 3 ) 2 ) 3 Stack 14 Push The Mass of ‘C’ Into The Stack 12

42. Visualization N(CH 2 (CH 3 ) 2 ) 3 Stack 14 Push The Mass of ‘H’ Into The Stack 12 1

43. Visualization N(CH 2 (CH 3 ) 2 ) 3 Stack 14 Multiply top of stack by 2 12 1

44. Visualization N(CH 2 (CH 3 ) 2 ) 3 Stack 14 Multiply top of stack by 2 12 2

45. Visualization N(CH 2 (CH 3 ) 2 ) 3 Stack 14 Start New Session 12 2

46. Visualization N(CH 2 (CH 3 ) 2 ) 3 Stack 14 Push The Mass of ‘C’ Into The Stack 12 2 12

47. Visualization N(CH 2 (CH 3 ) 2 ) 3 Stack 14 Push The Mass of ‘H’ Into The Stack 12 2 12 1

48. Visualization N(CH 2 (CH 3 ) 2 ) 3 Stack 14 Multiply Top Of Stack by 3 12 2 12 1

49. Visualization N(CH 2 (CH 3 ) 2 ) 3 Stack 14 Multiply Top Of Stack by 3 12 2 12 3

50. Visualization N(CH 2 (CH 3 ) 2 ) 3 Stack 14 Accumulate 12 2 12 3 3 + 12 = 15

51. Visualization N(CH 2 (CH 3 ) 2 ) 3 Stack 14 Push Result 12 2 15 3 + 12 = 15

52. Visualization N(CH 2 (CH 3 ) 2 ) 3 Stack 14 Multiply Top of Stack by 2 12 2 15

53. Visualization N(CH 2 (CH 3 ) 2 ) 3 Stack 14 Accumulate 12 2 30 30 + 2 + 12 = 44

54. Visualization N(CH 2 (CH 3 ) 2 ) 3 Stack 14 Push Result 44 30 + 2 + 12 = 44

55. Visualization N(CH 2 (CH 3 ) 2 ) 3 Stack 14 Multiply Top of Stack by 3 44

56. Visualization N(CH 2 (CH 3 ) 2 ) 3 Stack 14 Multiply Top of Stack by 3 132

57. Visualization N(CH 2 (CH 3 ) 2 ) 3 Stack 14 Accumulate all values 132 132 + 14 = 146

58.  Summary Start a new session by pushing “-1” (or any other invalid mass values that you desire). Push the mass of each atom when you encounter them. Multiply top of stack each time you encounter a number. Accumulate all values (until stack is empty or you pop a “session start” value). When done iterating, some all values in the stack (without counting the invalid value, of course).