1
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So we need a function which maps
the numbers zero through 51.

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00:00:04,370 --> 00:00:08,750
To each of the 52 cards in
a standard deck of cards.

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00:00:08,750 --> 00:00:10,280
Here's how we're going to do it.

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00:00:10,280 --> 00:00:14,460
First, the value of a card will
be equal to the index mod 13.

5
00:00:14,460 --> 00:00:17,790
There are thirteen cards of each suit.

6
00:00:17,790 --> 00:00:23,420
So taking the index mod thirteen will
give us four sets of zero through 12.

7
00:00:23,420 --> 00:00:24,250
Perfect.

8
00:00:24,250 --> 00:00:29,940
Second, the suit of a card will be split
out based on the index divided by 13.

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00:00:29,940 --> 00:00:34,260
Which, since they're both integers,
will result in an integer.

10
00:00:34,260 --> 00:00:38,950
Leaving us with a nice breakdown of zeros,
ones, twos and threes.

11
00:00:38,950 --> 00:00:42,530
Then, we just need to choose which
number represents which suit.

12
00:00:42,530 --> 00:00:43,940
And we're done.

13
00:00:43,940 --> 00:00:44,640
Cool.

14
00:00:44,640 --> 00:00:46,630
Let's add some space
above our cards array,.

15
00:00:46,630 --> 00:00:47,900
And get to work on this function.

16
00:00:49,910 --> 00:00:51,810
Start with the fun keyword.

17
00:00:51,810 --> 00:00:54,740
And then let's name it, index to card.

18
00:00:56,080 --> 00:01:00,170
Then, for the parameter,
let's pass in i and make it an int.

19
00:01:01,190 --> 00:01:06,150
Then let's add a colon, and
specify card as the return type.

20
00:01:06,150 --> 00:01:07,000
And then add our brackets.

21
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Then, let's make a new val named value.

22
00:01:12,210 --> 00:01:16,540
And set it equal to i mod 13.

23
00:01:16,540 --> 00:01:19,750
And let's make another new val,
named suit.

24
00:01:21,690 --> 00:01:28,050
And set it equal to when I,
divided by thirteen.

25
00:01:29,660 --> 00:01:30,682
And then add brackets.

26
00:01:30,682 --> 00:01:37,770
In Kotlin, instead of the switch
statement, we have the win statement.

27
00:01:37,770 --> 00:01:39,180
And it looks like this.

28
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So when I divided by thirteen is zero.

29
00:01:42,400 --> 00:01:45,220
Let's set suit equal to clubs.

30
00:01:46,460 --> 00:01:53,101
Then let's set command or
control+D three times, And

31
00:01:53,101 --> 00:01:59,296
then let's change these

32
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to 1 and diamonds.

33
00:02:04,317 --> 00:02:07,810
2 and

34
00:02:07,810 --> 00:02:12,000
hearts.

35
00:02:12,000 --> 00:02:14,890
And three with spades.

36
00:02:19,470 --> 00:02:20,220
Cool.

37
00:02:20,220 --> 00:02:21,870
But we're getting an error that.

38
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When expression must be exhaustive.

39
00:02:26,150 --> 00:02:28,400
Add necessary else branch.

40
00:02:28,400 --> 00:02:32,600
Normally, you can write a when statement
without needing an else branch.

41
00:02:32,600 --> 00:02:37,060
But since we're using this when
statement to populate our suit property.

42
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It must return a value.

43
00:02:38,990 --> 00:02:43,570
So lets just change the three to an else.

44
00:02:43,570 --> 00:02:44,920
And we're good to go.

45
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All that's left is to
return a new card instance.

46
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Return card of value and suit.

47
00:02:53,740 --> 00:02:54,580
All right.

48
00:02:54,580 --> 00:02:57,940
We've got our function
mapping each index to a card.

49
00:02:57,940 --> 00:03:02,800
Now we just need to pass in this function
as the second parameter to our array.

50
00:03:02,800 --> 00:03:06,940
Unfortunately, we can't just
pass in the name of a function.

51
00:03:06,940 --> 00:03:10,720
But what we can do,
is pass in anonymous function.

52
00:03:10,720 --> 00:03:16,400
To make a function anonymous in Kotlin,
all we have to do is remove the name.

53
00:03:17,850 --> 00:03:22,910
We can then store this function and
a variable like that.

54
00:03:22,910 --> 00:03:25,810
And then use this variable
down here in our array.

55
00:03:27,700 --> 00:03:29,470
Or, even better, we can just cut and

56
00:03:29,470 --> 00:03:32,052
paste the whole function
into the second parameter.

57
00:03:43,934 --> 00:03:49,655
And now, when we create a new deck,
we'll be ready with all 52 cards.

58
00:03:49,655 --> 00:03:51,085
But we're not done yet.

59
00:03:51,085 --> 00:03:53,525
This code can still look a bit better.

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And we'll see how in the next video.