Description
Question 1 [20 points]
Consider the following recursive function on positive integers:
foo(0) = 0
foo(1) = 1
foo(2) = 2
foo(n) = f(n-3) + f(n-2) – f(n-1) – 1 for n > 2
Write a function that gets an integer n and computes foo(n).
long foo(int n)
Your function should return the correct answer in reasonable time on inputs up to 1000.
Question 2 [30 points (15 points each item)]
Consider the struct
typedef struct {
char* name;
int id;
} person;
(see .h file for the definition of person)
A. Implement the recursive version of the linear search algorithm.
The function gets an (unsorted) array of length n with elements of type person, and an ID.
The output of the function is the index of the item in the array that contains the person with
the given ID. If A does not contain the item, the function returns -1.
int linear_search_rec(const person* A, int n, int id)
B. Implement the recursive version of the binary search algorithm.
The function gets an array sorted by ID of length n with elements of type person, and an
ID. The output of the function is the index of the item in the array that contains the person
with the given ID. If A does not contain the item, the function returns -1.
int binary_search_rec(const person* A, int n, int id)
Question 3 [35 points]
Write a function that gets an NxN matrix of colors, and a starting point, and colors the
WHITE area connected to the starting point with RED.
See examples below:
The green point on the left represents the starting point.
The red points are the area containing the starting point.
Specifically, the colors are represented as ints:
WHITE is corresponds to the number 0, RED corresponds to 1.
All other numbers are treated as other colors.
The arguments of the function are the dimensions of the array and the starting point
(see .h file for the definition of the type point)
void flood_fill(int N, int ar[N][N], point start)
The function colors the array as in flood fill algorithm.
Your function should work in reasonable time on arrays of size up to 50×50.
[Hint: use recursion]
[Hint2: the code should not be longer than 15 lines]
Question 4 [40 points (20 points each)]
Write the following two functions maintaining a database of entries of type person in a file.
(see .h file for the definition of point)
person* find_person(const char* file_name, int ID)
The function gets a name of a file and searches the file for a person with the given ID.
It returns a pointer to the struct person (on heap) with the name and ID of the person.
If the file does not exist or if the person with the required ID is not in the file, the function
returns the NULL pointer.
The file should not be changed by this function.
int add_person(const char* file_name, person p)
The function gets a name of a file, and a person p.
If the person with the same ID is already in the file, the function does nothing.
If the person is not in the file, the function adds p to the file.
If the file does not exist, a new file is created and the person is added to the file.
The function returns 0 if the person is added to the file.
The function returns 1 if the person has already been in the file.
The function returns -1 if there was an error (e.g. error opening a file).
Additional instructions and hints:
1) For the instructions on how to read and write to files see section “C Programming
Files” in https://www.programiz.com/c-programming or
https://www.tutorialspoint.com/cprogramming/c_file_io.htm or any other online
resources.
2) There are no specific instructions about how you should store the information in the
file. The only requirement is that the two functions are compatible with each other.
That is, if a person is added using add_person, then find_person will be able to
find it.
You should decide carefully on the format for storing the data of each person.
3) When storing the name, remember that you need to store the name and not the
pointer to it. Also, it may be convenient to store the length of the name in the file.
4) Don’t forget to close the file at the end of each function.
