Two Bucket in Python
Given two buckets of different size, demonstrate how to measure an exact number of liters.
exercism fetch python two-bucket
Given two buckets of different size, demonstrate how to measure an exact number of liters by strategically transferring liters of fluid between the buckets.
Since this mathematical problem is fairly subject to interpretation / individual approach, the tests have been written specifically to expect one overarching solution.
To help, the tests provide you with which bucket to fill first. That means, when starting with the larger bucket full, you are NOT allowed at any point to have the smaller bucket full and the larger bucket empty (aka, the opposite starting point); that would defeat the purpose of comparing both approaches!
Your program will take as input:
- the size of bucket one
- the size of bucket two
- the desired number of liters to reach
- which bucket to fill first, either bucket one or bucket two
Your program should determine:
- the total number of "moves" it should take to reach the desired number of liters, including the first fill
- which bucket should end up with the desired number of liters (let's say this is bucket A) - either bucket one or bucket two
- how many liters are left in the other bucket (bucket B)
Note: any time a change is made to either or both buckets counts as one (1) move.
Example: Bucket one can hold up to 7 liters, and bucket two can hold up to 11 liters. Let's say bucket one, at a given step, is holding 7 liters, and bucket two is holding 8 liters (7,8). If you empty bucket one and make no change to bucket two, leaving you with 0 liters and 8 liters respectively (0,8), that counts as one "move". Instead, if you had poured from bucket one into bucket two until bucket two was full, leaving you with 4 liters in bucket one and 11 liters in bucket two (4,11), that would count as only one "move" as well.
To conclude, the only valid moves are:
- pouring from one bucket to another
- emptying one bucket and doing nothing to the other
- filling one bucket and doing nothing to the other
Written with <3 at Fullstack Academy by Lindsay Levine.
Sometimes it is necessary to raise an exception. When you do this, you should include a meaningful error message to indicate what the source of the error is. This makes your code more readable and helps significantly with debugging. Not every exercise will require you to raise an exception, but for those that do, the tests will only pass if you include a message.
To raise a message with an exception, just write it as an argument to the exception type. For example, instead of
raise Exception, you should write:
raise Exception("Meaningful message indicating the source of the error")
Running the tests
To run the tests, run the appropriate command below (why they are different):
- Python 2.7:
- Python 3.4+:
Alternatively, you can tell Python to run the pytest module (allowing the same command to be used regardless of Python version):
python -m pytest two_bucket_test.py
-v: enable verbose output
-x: stop running tests on first failure
--ff: run failures from previous test before running other test cases
For other options, see
python -m pytest -h
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Water Pouring Problem http://demonstrations.wolfram.com/WaterPouringProblem/
Submitting Incomplete Solutions
It's possible to submit an incomplete solution so you can see how others have completed the exercise.