Submitted By: Mohammad S Anwar
You are asked to sell juice each costs $5. You are given an array of bills. You can only sell ONE juice to each customer but make sure you return exact change back. You only have $5, $10 and $20 notes. You do not have any change in hand at first.
Write a script to find out if it is possible to sell to each customers with correct change.
Input: @bills = (5, 5, 5, 10, 20) Output: true From the first 3 customers, we collect three $5 bills in order. From the fourth customer, we collect a $10 bill and give back a $5. From the fifth customer, we give a $10 bill and a $5 bill. Since all customers got correct change, we output true.
Input: @bills = (5, 5, 10, 10, 20) Output: false From the first two customers in order, we collect two $5 bills. For the next two customers in order, we collect a $10 bill and give back a $5 bill. For the last customer, we can not give the change of $15 back because we only have two $10 bills. Since not every customer received the correct change, the answer is false.
Input: @bills = (5, 5, 5, 20) Output: true
We'll us a hash to keep track of the number of each bill in the till. We'll start with no bills in the till, and then for each bill received, we'll increment the count of that bill in the till.
If the bill is a $10, we'll decrement the count of $5 bills in the till.
If the bill is a $20, we'll also decrement the count of $5 bills in the till, and if there are no $10 bills in the till, we'll decrement the count of $5 bills in the till by another 2.
If the count of $5 bills in the till ever goes negative, then we can't make change, and we return 'false'.
1| multi sub MAIN (
2| *@input where all(@input) ~~ 5|10|20,
3| --> Str
4| ) {
5| my Int %bills = (5 => 0, 10 => 0, 20 => 0);
6| my Str $retval = 'true';
7| for @input -> $bill {
8| %bills{$bill}++;
9|
10| given $bill {
11| when 10 { %bills{5}-- }
12| when 20 {
13| %bills{5}--;
14| %bills{10} > 0
15| ?? (%bills{10} -= 1)
16| !! (%bills{5} -= 2);
17| }
18| }
19|
20| if %bills{5} < 0 {
21| $retval = 'false';
22| last;
23| }
24| }
25| say $retval; 26| return $retval;; 27| }
(The option --verbose and the debug print statements are not shown in the above code.)
$ ./ch-1.raku -verbose 5 5 10 20 Received $5, have 1 $5s, 0 $10s, and 0 $20s in the till Received $5, have 2 $5s, 0 $10s, and 0 $20s in the till Received $10, have 1 $5s, 1 $10s, and 0 $20s in the till Received $20, have 0 $5s, 0 $10s, and 1 $20s in the till true ./ch-1.raku -verbose 5 5 10 10 20 Received $5, have 1 $5s, 0 $10s, and 0 $20s in the till Received $5, have 2 $5s, 0 $10s, and 0 $20s in the till Received $10, have 1 $5s, 1 $10s, and 0 $20s in the till Received $10, have 0 $5s, 2 $10s, and 0 $20s in the till Received $20, have -1 $5s, 1 $10s, and 1 $20s in the till false
Shimon Bollinger (deoac.shimon@gmail.com)
Comments and Pull Requests are welcome.
The complete source code for this solution can be found at Challenge 236, Task 1
© 2023 Shimon Bollinger. All rights reserved.
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