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fp:lab01-java-intro [2021/03/11 13:17] pdmatei |
fp:lab01-java-intro [2021/03/11 14:50] (current) dmihai |
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| ===== 1. A single function to implement all of them ===== | ===== 1. A single function to implement all of them ===== | ||
| - | 1.1. Write a method that takes a list of integers and returns a new list with all elements multiplied by two. | + | 1.1. Write a method that takes a list of **integers** and returns a new list with all elements multiplied by two. |
| - | 1.2. Write a method that takes a list of doubles and returns a new list with all elements multiplied by two. | + | 1.2. Write a method that takes a list of **doubles** and returns a new list with all elements multiplied by two. |
| 1.3. Write a method that takes a list of integers and returns a new list with all the elements’ successors (i.e. the elements incremented by 1). | 1.3. Write a method that takes a list of integers and returns a new list with all the elements’ successors (i.e. the elements incremented by 1). | ||
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| 1.6. (Discussion) How can we pass **functions** as parameter (to another function) in Java? Consider **unary** functions of the form: $math[f : A \rightarrow B] (where $math[A] and $math[B] are generic). | 1.6. (Discussion) How can we pass **functions** as parameter (to another function) in Java? Consider **unary** functions of the form: $math[f : A \rightarrow B] (where $math[A] and $math[B] are generic). | ||
| - | 1.7. (!) Write an implementation for ''map''. | + | 1.7. (!) Write an implementation for ''map'' and use ''map'' to solve 1.4. |
| - | ===== Throwing out elements ... ===== | + | ===== 2. Throwing out elements ... ===== |
| 2.1. Write a method that takes a list of integers and returns a new list containing only even elements. | 2.1. Write a method that takes a list of integers and returns a new list containing only even elements. | ||
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| 2.3. Write a method that takes a list of integers and returns a new list containing **even** elements **larger** than 100. | 2.3. Write a method that takes a list of integers and returns a new list containing **even** elements **larger** than 100. | ||
| - | d. Write a method that takes a list of integers and returns a new list of the elements which are prime | + | 2.4. Write a method that takes a list of strings and returns a new list of strings which start with letter ''B'' only. |
| - | 2.4. (!) Write the signature of a generic ''filter'' function over lists. | + | 2.5. (!) Write the signature of a generic ''filter'' function over lists. |
| - | 2.5. (!!) Implement ''filter''. | + | 2.6. (!!) Implement ''filter''. |
| + | ===== 3. Reducing lists ===== | ||
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| + | 3.1. Write a method that takes a list of integers and returns the sum of all the elements. | ||
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| + | 3.2. Write a method that takes a list of integers and returns the product of all the elements. | ||
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| + | 3.3. Write a method that takes a list of integers and returns a string representation of all elements separated by commas, e.g. “1,2,3,4” | ||
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| + | 3.4. Write a method that takes a list of integers and returns their greatest common denominator. | ||
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| + | 3.5. (Discussion) What is (could be!) common among all implementations? How should a ''fold'' function **signature** (which generalises over all previous ones) look like? | ||
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| + | 3.6. (!) Implement ''fold'' with all its prerequisites and use it to solve 3.4. | ||
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| + | ===== 4. Zipping lists ===== | ||
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| + | 4.1. Write a method that takes two lists and returns a new list of all pairwise products. E.g. ''[2, 4, 2''] and ''[6, 7, 8]'' should yield ''[12, 28, 16]'' | ||
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| + | 4.2. Write a method that takes two lists and returns a new list of all pairwise sums. E.g. ''[2, 4, 2]'' and ''[6, 7, 8]'' should yield ''[8, 11, 10]'' | ||
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| + | 4.3. Write a method that takes a list and returns a new list with the square of each element. | ||
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| + | 4.4. (!) Identify a generic function which can replace all the above, and implement it. Solve 4.3. using it. | ||