COMP3023 Programming Assignment
Shooting Competition
Philoctetes is a sharp shooter. One day he is invited by a shooting competition.
In the competition, each shooter is given an array of n targets. Every target
has a value, a positive integer. If one target t is shot, the shooter’s scores will
be increased by
v1 × v2 × v3
where v1 is the value on the target t, v2 is the value on t’s left neighbor, and v3
is the value on t’s right neighbor.
You need to design a greed algorithm and a dynamic programming algorithm
to find an shooting order to maximize the score earned by Philoctetes under the
following assumptions.
1. Philoctetes never misses any target.
2. Shooters know the value on every target before shooting.
3. Each target has only two neighbors, left and right.
4. If one target is shot, its left and right neighbors will be neighbors afterwards.
5. Pretend that the first target has an artificial left neighbor - target 0.
Philoctetes cannot shoot target 0, but the target has value 1 and will be
counted in the score calculation.
6. Similarly, the right nieghbor of the last target is also an artificial target
n + 1 of value 1, which cannot be shot.
Requirements
1. Algorithms
(a) The greedy algorithm runs in O(n log n) time and uses O(1) space.
The greedy algorithm is not required to always find the maximum
score.
(b) The dynamic programming runs in O(n
2
) time and uses O(n
2
) space.
It always gives the maximum score.
1
2. Program
(a) You need to implement your algorithms in C.
(b) Your program reads a test case from “input.txt”.
(c) “input.txt” only contains the values for each target, one value on
each line.
(d) Your program outputs the resulting score on the screen and the corresponding
shooting sequence to “output.txt”, one index of a target
on each line.
3. Report
(a) Your report should contain all the notations that you have used to
model the problem,
(b) the recurrent relation for the dynamic programming,
(c) step-by-step pseudo codes for the two algorithms with clearly described
inputs and outputs,
(d) an instance such that your greedy algorithm cannot find the maximum
solution,
(e) space and time complexity anlysis of your algorithms.
(f) Your report should be 2 to 3 pages long, depends how you write.
4. Submission includs your code and your report. Name the package as
“COMP3023 20F PA #########.zip”, where #########
is your student ID.
Example
Suppose Philoctetes is given 4 targes of values 2, 1, 4, 3 (see “input example.txt”),
the maximum score is 41 because
Iteration Target index Score Values of the remaining targets
1 Target 2 (valued 1) 0 + 2 × 1 × 4 2, 4, 3
2 Target 3 (valued 4) 8 + 2 × 4 × 3 2, 3
3 Target 1 (valued 2) 32 + 1 × 2 × 3 3
4 Target 4 (valued 3) 38 + 1 × 3 × 1 Empty
The shooting sequence 2, 3, 1, 4 is in “output example.txt”.