handout #11
CSE143—Computer Programming II
Programming Assignment #4
due: Friday,
This assignment will give you practice with queues. You are going to implement a class that computes all the primes up to some integer n. The technique you are to use was developed by a Greek named Eratosthenes who lived in the third century BC. The technique is known as the Sieve of Eratosthenes.
The algorithm is described by the following pseudocode:
create a
queue and fill it with the consecutive integers 2 through n inclusive.
create an empty queue to store primes.
do {
obtain the next prime by removing the
first value in the queue of numbers.
put the next
prime into the queue of primes.
go through
the queue of numbers, eliminating numbers divisible by the next prime.
} while (the next prime < sqrt(n))
all remaining values in numbers queue are prime, so transfer them to primes
queue
You are to use the Queue interface discussed in lecture (handout #10). When you want to construct a Queue object, you should make it of type LinkedQueue. These classes will be included in the zip file for the assignment.
You should define a class called Sieve with the following public methods:
Method |
Description |
Sieve() |
Constructs a sieve object. |
void computeTo(int n) |
Computes all primes up to and including n. Throws an IllegalArgumentException if n is less than 2. |
void reportResults() |
Reports the primes to System.out. Throws an IllegalStateException if no legal call has been made yet on the computeTo method. |
int getMax() |
Returns the maximum value used in the last call on computeTo (i.e., the last “n” that was passed to computeTo, which is the last n examined, not the maximum prime found). Throws an IllegalStateException if no legal call has been made yet on the computeTo method. |
int getCount() |
Returns the number of primes found in the last call on computeTo. Throws an IllegalStateException if no legal call has been made yet on the computeTo method. |
Your reportResults method should print the maximum n used and should then show a list of the primes, 12 per line with a space after each prime. Notice that there is no guarantee that the number of primes will be a multiple of 12. The calls on reportResults must exactly reproduce the format of the sample log. The final line of output that appears in the log reporting the percentage of primes is generated by the main program, not by the call on reportResults.
Even though you will be using a LinkedQueue object to write this program, you should use variables of type Queue. It should be possible for someone to replace all calls on the LinkedQueue constructor with calls on the constructor of another class that implements the Queue interface and the rest of your code should work without modification. You should also be sure to specify that we want queues of “Integer” (Queue<Integer> and LinkedQueue<Integer>). If you fail to specify this properly, the compiler will warn you that you are using “unsafe” operations.
You must guarantee that your
object is never in a corrupt state. For
example, your sieve object might be asked to compute up to one value of n and
then asked to compute up to a different value of n without a call on reportResults ever being made. Similarly, your object might be asked to
compute up to some value of n and then be asked to reportResults
more than once. Each call on reportResults, getMax and getCount should behave appropriately given the previous
call on computeTo, no matter how often they are
called or in what order. Finally, notice
that if reportResults, getMax
or getCount are called before a legal call on computeTo, they throw an exception to indicate that the
operation is not legal given the object’s state.
The zip file for this assignment includes a file SieveMain.java that constructs a sieve object and makes calls on it based on values entered by the user. You can use this program to test your class, but keep in mind that it does not test the internal consistency of your object.
In terms of correctness, your class must provide
all of the functionality described above.
In terms of style, we will be grading on your use of comments, good
variable names, consistent indentation and good coding style to implement these
operations. Remember that you will lose
points if you declare variables as data fields that can instead be declared as
local variables.
You should name your file Sieve.java
and you should turn it in electronically from the “assignments” link on the
class web page. A collection of files
needed for the assignment is included on the web page as ass4.zip. You will need to have Queue.java
and LinkedQueue.java in the same directory as your Sieve.java in order to run SieveMain.
Log of Execution (user responses underlined)
This program computes all prime numbers up to a
maximum using the Sieve of
Eratosthenes.
Maximum n to compute (0 to quit)? 20
Primes up to 20 are as follows:
2 3 5 7 11 13 17 19
% of primes = 40
Maximum n to compute (0 to quit)? 100
Primes up to 100 are as follows:
2 3 5 7 11 13 17 19 23 29 31 37
41 43 47 53 59 61 67 71 73 79 83 89
97
% of primes = 25
Maximum n to compute (0 to quit)? 500
Primes up to 500 are as follows:
2 3 5 7 11 13 17 19 23 29 31 37
41 43 47 53 59 61 67 71 73 79 83 89
97 101 103 107 109 113 127 131 137 139 149 151
157 163 167 173 179 181 191 193 197 199 211 223
227 229 233 239 241 251 257 263 269 271 277 281
283 293 307 311 313 317 331 337 347 349 353 359
367 373 379 383 389 397 401 409 419 421 431 433
439 443 449 457 461 463 467 479 487 491 499
% of primes = 19
Maximum n to compute (0 to quit)? 1000
Primes up to 1000 are as follows:
2 3 5 7 11 13 17 19 23 29 31 37
41 43 47 53 59 61 67 71 73 79 83 89
97 101 103 107 109 113 127 131 137 139 149 151
157 163 167 173 179 181 191 193 197 199 211 223
227 229 233 239 241 251 257 263 269 271 277 281
283 293 307 311 313 317 331 337 347 349 353 359
367 373 379 383 389 397 401 409 419 421 431 433
439 443 449 457 461 463 467 479 487 491 499 503
509 521 523 541 547 557 563 569 571 577 587 593
599 601 607 613 617 619 631 641 643 647 653 659
661 673 677 683 691 701 709 719 727 733 739 743
751 757 761 769 773 787 797 809 811 821 823 827
829 839 853 857 859 863 877 881 883 887 907 911
919 929 937 941 947 953 967 971 977 983 991 997
% of primes = 16
Maximum n to compute (0 to quit)? 5000
Primes up to 5000 are as follows:
2 3 5 7 11 13 17 19 23 29 31 37
41 43 47 53 59 61 67 71 73 79 83 89
97 101 103 107 109 113 127 131 137 139 149 151
157 163 167 173 179 181 191 193 197 199 211 223
227 229 233 239 241 251 257 263 269 271 277 281
283 293 307 311 313 317 331 337 347 349 353 359
367 373 379 383 389 397 401 409 419 421 431 433
439 443 449 457 461 463 467 479 487 491 499 503
509 521 523 541 547 557 563 569 571 577 587 593
599 601 607 613 617 619 631 641 643 647 653 659
661 673 677 683 691 701 709 719 727 733 739 743
751 757 761 769 773 787 797 809 811 821 823 827
829 839 853 857 859 863 877 881 883 887 907 911
919 929 937 941 947 953 967 971 977 983 991 997
1009 1013 1019 1021 1031 1033 1039 1049 1051 1061 1063
1069
1087 1091 1093 1097 1103 1109 1117 1123 1129 1151 1153
1163
1171 1181 1187 1193 1201 1213 1217 1223 1229 1231 1237
1249
1259 1277 1279 1283 1289 1291 1297 1301 1303 1307 1319
1321
1327 1361 1367 1373 1381 1399 1409 1423 1427 1429 1433
1439
1447 1451 1453 1459 1471 1481 1483 1487 1489 1493 1499
1511
1523 1531 1543 1549 1553 1559 1567 1571 1579 1583 1597
1601
1607 1609 1613 1619 1621 1627 1637 1657 1663 1667 1669
1693
1697 1699 1709 1721 1723 1733 1741 1747 1753 1759 1777
1783
1787 1789 1801 1811 1823 1831 1847 1861 1867 1871 1873
1877
1879 1889 1901 1907 1913 1931 1933 1949 1951 1973 1979
1987
1993 1997 1999 2003 2011 2017 2027 2029 2039 2053 2063
2069
2081 2083 2087 2089 2099 2111 2113 2129 2131 2137 2141
2143
2153 2161 2179 2203 2207 2213 2221 2237 2239 2243 2251 2267
2269 2273 2281 2287 2293 2297 2309 2311 2333 2339 2341
2347
2351 2357 2371 2377 2381 2383 2389 2393 2399 2411 2417
2423
2437 2441 2447 2459 2467 2473 2477 2503 2521 2531 2539
2543
2549 2551 2557 2579 2591 2593 2609 2617 2621 2633 2647
2657
2659 2663 2671 2677 2683 2687 2689 2693 2699 2707 2711
2713
2719 2729 2731 2741 2749 2753 2767 2777 2789 2791 2797
2801
2803 2819 2833 2837 2843 2851 2857 2861 2879 2887 2897
2903
2909 2917 2927 2939 2953 2957 2963 2969 2971 2999 3001
3011
3019 3023 3037 3041 3049 3061 3067 3079 3083 3089 3109
3119
3121 3137 3163 3167 3169 3181 3187 3191 3203 3209 3217
3221
3229 3251 3253 3257 3259 3271 3299 3301 3307 3313 3319
3323
3329 3331 3343 3347 3359 3361 3371 3373 3389 3391 3407
3413
3433 3449 3457 3461 3463 3467 3469 3491 3499 3511 3517
3527
3529 3533 3539 3541 3547 3557 3559 3571 3581 3583 3593
3607
3613 3617 3623 3631 3637 3643 3659 3671 3673 3677 3691
3697
3701 3709 3719 3727 3733 3739 3761 3767 3769 3779 3793
3797
3803 3821 3823 3833 3847 3851 3853 3863 3877 3881 3889
3907
3911 3917 3919 3923 3929 3931 3943 3947 3967 3989 4001
4003
4007 4013 4019 4021 4027 4049 4051 4057 4073 4079 4091
4093
4099 4111 4127 4129 4133 4139 4153 4157 4159 4177 4201
4211
4217 4219 4229 4231 4241 4243 4253 4259 4261 4271 4273 4283
4289 4297 4327 4337 4339 4349 4357 4363 4373 4391 4397
4409
4421 4423 4441 4447 4451 4457 4463 4481 4483 4493 4507
4513
4517 4519 4523 4547 4549 4561 4567 4583 4591 4597 4603
4621
4637 4639 4643 4649 4651 4657 4663 4673 4679 4691 4703
4721
4723 4729 4733 4751 4759 4783 4787 4789 4793 4799 4801
4813
4817 4831 4861 4871 4877 4889 4903 4909 4919 4931 4933
4937
4943 4951 4957 4967 4969 4973 4987 4993 4999
% of primes = 13
Maximum n to compute (0 to quit)? 0