Add perfect-numbers exercise

config.json

@@ -234,6 +234,14 @@
         "prerequisites": [],
         "difficulty": 4
       },
+      {
+        "slug": "perfect-numbers",
+        "name": "Perfect Numbers",
+        "uuid": "f3a67356-dca2-4cd6-87dc-8e7558d31381",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 4
+      },
       {
         "slug": "phone-number",
         "name": "Phone Number",

exercises/practice/perfect-numbers/.docs/instructions.md

@@ -0,0 +1,39 @@
+# Instructions
+
+Determine if a number is perfect, abundant, or deficient based on Nicomachus' (60 - 120 CE) classification scheme for positive integers.
+
+The Greek mathematician [Nicomachus][nicomachus] devised a classification scheme for positive integers, identifying each as belonging uniquely to the categories of [perfect](#perfect), [abundant](#abundant), or [deficient](#deficient) based on their [aliquot sum][aliquot-sum].
+The _aliquot sum_ is defined as the sum of the factors of a number not including the number itself.
+For example, the aliquot sum of `15` is `1 + 3 + 5 = 9`.
+
+## Perfect
+
+A number is perfect when it equals its aliquot sum.
+For example:
+
+- `6` is a perfect number because `1 + 2 + 3 = 6`
+- `28` is a perfect number because `1 + 2 + 4 + 7 + 14 = 28`
+
+## Abundant
+
+A number is abundant when it is less than its aliquot sum.
+For example:
+
+- `12` is an abundant number because `1 + 2 + 3 + 4 + 6 = 16`
+- `24` is an abundant number because `1 + 2 + 3 + 4 + 6 + 8 + 12 = 36`
+
+## Deficient
+
+A number is deficient when it is greater than its aliquot sum.
+For example:
+
+- `8` is a deficient number because `1 + 2 + 4 = 7`
+- Prime numbers are deficient
+
+## Task
+
+Implement a way to determine whether a given number is [perfect](#perfect).
+Depending on your language track, you may also need to implement a way to determine whether a given number is [abundant](#abundant) or [deficient](#deficient).
+
+[nicomachus]: https://en.wikipedia.org/wiki/Nicomachus
+[aliquot-sum]: https://en.wikipedia.org/wiki/Aliquot_sum

exercises/practice/perfect-numbers/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "keiravillekode"
+  ],
+  "files": {
+    "solution": [
+      "perfect_numbers.s"
+    ],
+    "test": [
+      "perfect_numbers_test.c"
+    ],
+    "example": [
+      ".meta/example.s"
+    ]
+  },
+  "blurb": "Determine if a number is perfect, abundant, or deficient based on Nicomachus' (60 - 120 CE) classification scheme for positive integers.",
+  "source": "Taken from Chapter 2 of Functional Thinking by Neal Ford.",
+  "source_url": "https://www.oreilly.com/library/view/functional-thinking/9781449365509/"
+}

exercises/practice/perfect-numbers/.meta/example.s

@@ -0,0 +1,62 @@
+.equ DEFICIENT, 1
+.equ PERFECT, 2
+.equ ABUNDANT, 3
+.equ INVALID, -1
+
+.text
+.globl classify
+
+/* extern int classify(int64_t number); */
+classify:
+        cmp     x0, #1
+        ble     .le_one
+
+        mov     x1, #1                  /* product of factors */
+        mov     x2, #1
+        lsl     x4, x0, #1              /* 2 * number */
+
+.next:
+        add     x2, x2, #1              /* candidate factor */
+        mov     x5, #1                  /* sum of powers of factor */
+        mul     x3, x2, x2
+        cmp     x3, x0
+        csel    x2, x0, x2, hi          /* if x2*x2 exceeds x0, then set x2 to x0 */
+
+        udiv    x6, x0, x2              /* quotient */
+        msub    x7, x6, x2, x0          /* remainder */
+        cbnz    x7, .next
+
+.repeat:
+        mul     x5, x5, x2
+        add     x5, x5, #1
+        mov     x0, x6
+
+        udiv    x6, x0, x2              /* quotient */
+        msub    x7, x6, x2, x0          /* remainder */
+        cbz     x7, .repeat
+
+        mul     x1, x1, x5
+        cmp     x0, #1
+        bne     .next
+
+        cmp     x1, x4
+        beq     .perfect
+        blo     .deficient
+
+.abundant:
+        mov     x0, ABUNDANT
+        ret
+
+.perfect:
+        mov     x0, PERFECT
+        ret
+
+.deficient:
+        mov     x0, DEFICIENT
+        ret
+
+.le_one:
+        beq     .deficient
+
+        mov     x0, INVALID
+        ret

exercises/practice/perfect-numbers/.meta/tests.toml

@@ -0,0 +1,49 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[163e8e86-7bfd-4ee2-bd68-d083dc3381a3]
+description = "Perfect numbers -> Smallest perfect number is classified correctly"
+
+[169a7854-0431-4ae0-9815-c3b6d967436d]
+description = "Perfect numbers -> Medium perfect number is classified correctly"
+
+[ee3627c4-7b36-4245-ba7c-8727d585f402]
+description = "Perfect numbers -> Large perfect number is classified correctly"
+
+[80ef7cf8-9ea8-49b9-8b2d-d9cb3db3ed7e]
+description = "Abundant numbers -> Smallest abundant number is classified correctly"
+
+[3e300e0d-1a12-4f11-8c48-d1027165ab60]
+description = "Abundant numbers -> Medium abundant number is classified correctly"
+
+[ec7792e6-8786-449c-b005-ce6dd89a772b]
+description = "Abundant numbers -> Large abundant number is classified correctly"
+
+[e610fdc7-2b6e-43c3-a51c-b70fb37413ba]
+description = "Deficient numbers -> Smallest prime deficient number is classified correctly"
+
+[0beb7f66-753a-443f-8075-ad7fbd9018f3]
+description = "Deficient numbers -> Smallest non-prime deficient number is classified correctly"
+
+[1c802e45-b4c6-4962-93d7-1cad245821ef]
+description = "Deficient numbers -> Medium deficient number is classified correctly"
+
+[47dd569f-9e5a-4a11-9a47-a4e91c8c28aa]
+description = "Deficient numbers -> Large deficient number is classified correctly"
+
+[a696dec8-6147-4d68-afad-d38de5476a56]
+description = "Deficient numbers -> Edge case (no factors other than itself) is classified correctly"
+
+[72445cee-660c-4d75-8506-6c40089dc302]
+description = "Invalid inputs -> Zero is rejected (as it is not a positive integer)"
+
+[2d72ce2c-6802-49ac-8ece-c790ba3dae13]
+description = "Invalid inputs -> Negative integer is rejected (as it is not a positive integer)"

exercises/practice/perfect-numbers/Makefile

@@ -0,0 +1,36 @@
+AS = aarch64-linux-gnu-as
+CC = aarch64-linux-gnu-gcc
+
+CFLAGS = -g -Wall -Wextra -pedantic -Werror
+LDFLAGS =
+
+ALL_LDFLAGS = -pie -Wl,--fatal-warnings
+
+ALL_CFLAGS = -std=c99 -fPIE $(CFLAGS)
+ALL_LDFLAGS += $(LDFLAGS)
+
+C_OBJS = $(patsubst %.c,%.o,$(wildcard *.c))
+AS_OBJS = $(patsubst %.s,%.o,$(wildcard *.s))
+ALL_OBJS = $(filter-out example.o,$(C_OBJS) $(AS_OBJS) vendor/unity.o)
+
+CC_CMD = $(CC) $(ALL_CFLAGS) -c -o $@ $<
+
+all: tests
+	qemu-aarch64 -L /usr/aarch64-linux-gnu ./$<
+
+tests: $(ALL_OBJS)
+	@$(CC) $(ALL_CFLAGS) $(ALL_LDFLAGS) -o $@ $(ALL_OBJS)
+
+%.o: %.s
+	@$(AS) -o $@ $<
+
+%.o: %.c
+	@$(CC_CMD)
+
+vendor/unity.o: vendor/unity.c vendor/unity.h vendor/unity_internals.h
+	@$(CC_CMD)
+
+clean:
+	@rm -f *.o vendor/*.o tests
+
+.PHONY: all clean

exercises/practice/perfect-numbers/perfect_numbers.s

@@ -0,0 +1,10 @@
+.equ DEFICIENT, 1
+.equ PERFECT, 2
+.equ ABUNDANT, 3
+.equ INVALID, -1
+
+.text
+.globl classify
+
+classify:
+    ret

exercises/practice/perfect-numbers/perfect_numbers_test.c

@@ -0,0 +1,104 @@
+#include "vendor/unity.h"
+
+#include <stdint.h>
+
+#define DEFICIENT 1
+#define PERFECT 2
+#define ABUNDANT 3
+#define INVALID -1
+
+extern int classify(int64_t number);
+
+void setUp(void) {
+}
+
+void tearDown(void) {
+}
+
+void test_smallest_perfect_number_is_classified_correctly(void) {
+    TEST_ASSERT_EQUAL_INT(PERFECT, classify(6));
+}
+
+void test_medium_perfect_number_is_classified_correctly(void) {
+    TEST_IGNORE();
+    TEST_ASSERT_EQUAL_INT(PERFECT, classify(28));
+}
+
+void test_large_perfect_number_is_classified_correctly(void) {
+    TEST_IGNORE();
+    TEST_ASSERT_EQUAL_INT(PERFECT, classify(33550336));
+}
+
+void test_smallest_abundant_number_is_classified_correctly(void) {
+    TEST_IGNORE();
+    TEST_ASSERT_EQUAL_INT(ABUNDANT, classify(12));
+}
+
+void test_medium_abundant_number_is_classified_correctly(void) {
+    TEST_IGNORE();
+    TEST_ASSERT_EQUAL_INT(ABUNDANT, classify(30));
+}
+
+void test_large_abundant_number_is_classified_correctly(void) {
+    TEST_IGNORE();
+    TEST_ASSERT_EQUAL_INT(ABUNDANT, classify(33550335));
+}
+
+void test_smallest_prime_deficient_number_is_classified_correctly(void) {
+    TEST_IGNORE();
+    TEST_ASSERT_EQUAL_INT(DEFICIENT, classify(2));
+}
+
+void test_smallest_nonprime_deficient_number_is_classified_correctly(void) {
+    TEST_IGNORE();
+    TEST_ASSERT_EQUAL_INT(DEFICIENT, classify(4));
+}
+
+void test_medium_deficient_number_is_classified_correctly(void) {
+    TEST_IGNORE();
+    TEST_ASSERT_EQUAL_INT(DEFICIENT, classify(32));
+}
+
+void test_large_deficient_number_is_classified_correctly(void) {
+    TEST_IGNORE();
+    TEST_ASSERT_EQUAL_INT(DEFICIENT, classify(33550337));
+}
+
+void test_edge_case_no_factors_other_than_itself_is_classified_correctly(void) {
+    TEST_IGNORE();
+    TEST_ASSERT_EQUAL_INT(DEFICIENT, classify(1));
+}
+
+void test_zero_is_rejected_as_it_is_not_a_positive_integer(void) {
+    TEST_IGNORE();
+    TEST_ASSERT_EQUAL_INT(INVALID, classify(0));
+}
+
+void test_negative_integer_is_rejected_as_it_is_not_a_positive_integer(void) {
+    TEST_IGNORE();
+    TEST_ASSERT_EQUAL_INT(INVALID, classify(-1));
+}
+
+void test_large_negative_is_rejected(void) {
+    TEST_IGNORE();
+    TEST_ASSERT_EQUAL_INT(INVALID, classify(-7001002003));
+}
+
+int main(void) {
+    UNITY_BEGIN();
+    RUN_TEST(test_smallest_perfect_number_is_classified_correctly);
+    RUN_TEST(test_medium_perfect_number_is_classified_correctly);
+    RUN_TEST(test_large_perfect_number_is_classified_correctly);
+    RUN_TEST(test_smallest_abundant_number_is_classified_correctly);
+    RUN_TEST(test_medium_abundant_number_is_classified_correctly);
+    RUN_TEST(test_large_abundant_number_is_classified_correctly);
+    RUN_TEST(test_smallest_prime_deficient_number_is_classified_correctly);
+    RUN_TEST(test_smallest_nonprime_deficient_number_is_classified_correctly);
+    RUN_TEST(test_medium_deficient_number_is_classified_correctly);
+    RUN_TEST(test_large_deficient_number_is_classified_correctly);
+    RUN_TEST(test_edge_case_no_factors_other_than_itself_is_classified_correctly);
+    RUN_TEST(test_zero_is_rejected_as_it_is_not_a_positive_integer);
+    RUN_TEST(test_negative_integer_is_rejected_as_it_is_not_a_positive_integer);
+    RUN_TEST(test_large_negative_is_rejected);
+    return UNITY_END();
+}