C: pythagorean-triplet and saddle-point

c/pythagorean-triplet/GNUmakefile

@@ -0,0 +1,51 @@
+# The original 'makefile' has a flaw:
+# 1) it overrides CFLAGS
+# 2) it does not pass extra "FLAGS" to $(CC) that could come from environment
+#
+# It means :
+# - we need to edit 'makefile' for different builds (DEBUG, etc...), which is
+#   not practical at all.
+# - Also, it does not allow to run all tests without editing the test source
+#   code.
+#
+# To use this makefile (GNU make only):
+#   "make": build with all predefined tests (without editing test source code)
+#   "make debugall": build with all predefined tests and debug code
+#   "make mem": perform memcheck with all tests enabled
+#   "make unit": build standalone (unit) test
+#   "make debug": build standalone test with debugging code
+#
+# Original 'makefile' targets can be used (test, memcheck, clean, ...)
+
+.PHONY: default all mem unit debug std debugtest
+
+default: all
+
+# default is to build with all predefined tests
+BUILD := teststall
+
+include makefile
+
+all: CFLAGS+=-DTESTALL
+all: clean test
+
+debugall: CFLAGS+=-DDEBUG
+debugall: all
+
+debugtest: CFLAGS+=-DDEBUG
+debugtest: test
+
+mem: CFLAGS+=-DTESTALL
+mem: clean memcheck
+
+unit: CFLAGS+=-DUNIT_TEST
+unit: clean std
+
+debug: CFLAGS+=-DUNIT_TEST -DDEBUG
+debug: clean std
+
+debugtest: CFLAGS+=-DDEBUG
+debugtest: test
+
+std: src/*.c src/*.h
+	$(CC) $(CFLAGS) src/*.c -o tests.out  $(LIBS)

c/pythagorean-triplet/README.md

@@ -0,0 +1,62 @@
+# Pythagorean Triplet
+
+A Pythagorean triplet is a set of three natural numbers, {a, b, c}, for
+which,
+
+```text
+a**2 + b**2 = c**2
+```
+
+and such that,
+
+```text
+a < b < c
+```
+
+For example,
+
+```text
+3**2 + 4**2 = 9 + 16 = 25 = 5**2.
+```
+
+Given an input integer N, find all Pythagorean triplets for which `a + b + c = N`.
+
+For example, with N = 1000, there is exactly one Pythagorean triplet for which `a + b + c = 1000`: `{200, 375, 425}`.
+
+## Getting Started
+
+Make sure you have read the "Guides" section of the
+[C track][c-track] on the Exercism site. This covers
+the basic information on setting up the development environment expected
+by the exercises.
+
+## Passing the Tests
+
+Get the first test compiling, linking and passing by following the [three
+rules of test-driven development][3-tdd-rules].
+
+The included makefile can be used to create and run the tests using the `test`
+task.
+
+    make test
+
+Create just the functions you need to satisfy any compiler errors and get the
+test to fail. Then write just enough code to get the test to pass. Once you've
+done that, move onto the next test.
+
+As you progress through the tests, take the time to refactor your
+implementation for readability and expressiveness and then go on to the next
+test.
+
+Try to use standard C99 facilities in preference to writing your own
+low-level algorithms or facilities by hand.
+
+## Source
+
+Problem 9 at Project Euler [http://projecteuler.net/problem=9](http://projecteuler.net/problem=9)
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.
+
+[c-track]: https://exercism.io/my/tracks/c
+[3-tdd-rules]: http://butunclebob.com/ArticleS.UncleBob.TheThreeRulesOfTdd

c/pythagorean-triplet/makefile

@@ -0,0 +1,37 @@
+### If you wish to use extra libraries (math.h for instance),
+### add their flags here (-lm in our case) in the "LIBS" variable.
+
+LIBS = -lm
+
+###
+CFLAGS  = -std=c99
+CFLAGS += -g
+CFLAGS += -Wall
+CFLAGS += -Wextra
+CFLAGS += -pedantic
+CFLAGS += -Werror
+CFLAGS += -Wmissing-declarations
+CFLAGS += -DUNITY_SUPPORT_64
+
+ASANFLAGS  = -fsanitize=address
+ASANFLAGS += -fno-common
+ASANFLAGS += -fno-omit-frame-pointer
+
+.PHONY: test
+test: tests.out
+	@./tests.out
+
+.PHONY: memcheck
+memcheck: test/*.c src/*.c src/*.h
+	@echo Compiling $@
+	@$(CC) $(ASANFLAGS) $(CFLAGS) src/*.c test/vendor/unity.c test/*.c -o memcheck.out $(LIBS)
+	@./memcheck.out
+	@echo "Memory check passed"
+
+.PHONY: clean
+clean:
+	rm -rf *.o *.out *.out.dSYM
+
+tests.out: test/*.c src/*.c src/*.h
+	@echo Compiling $@
+	@$(CC) $(CFLAGS) src/*.c test/vendor/unity.c test/*.c -o tests.out $(LIBS)

c/pythagorean-triplet/src/pythagorean_triplet.c

@@ -0,0 +1,89 @@
+#include <malloc.h>
+
+#include "pythagorean_triplet.h"
+
+#define POOL_SIZE 10
+
+/* V1: initial version
+ * V2: cormetic changes
+ * V3: add pool for realloc instead of single realloc
+ */
+void free_triplets(triplets_t *t)
+{
+    free(t->triplets);
+    free(t);
+}
+
+static triplets_t *new_triplet()
+{
+    triplets_t *t=malloc(sizeof(triplets_t));
+    if (t) {
+        t->count = 0;
+        t->pool  = 0;
+        t->triplets = NULL;
+    }
+    return t;
+}
+
+static triplets_t *add_triplet(triplets_t *t, const uint16_t a, const uint16_t b,
+                               const uint16_t c)
+{
+    /* we may directly call add_triplet() without new_triplet. Not used here,
+     * but could be useful if triplets_with_sum() would return NULL when no
+     * solution found.
+     */
+    if (! (t || (t = new_triplet())))
+        return NULL;
+
+    if (t->count == t->pool) {
+        t->pool += POOL_SIZE;
+        if (!(t->triplets = realloc(t->triplets, sizeof(triplets_t) +
+                                    t->pool * sizeof(triplet_t)))) {
+            free(t);
+            return NULL;
+        }
+    }
+    t->triplets[t->count] = (triplet_t) {a, b, c};
+    t->count++;
+    return t;
+}
+
+/* algorithm from : https://stackoverflow.com/a/2818750/3079831
+ */
+triplets_t *triplets_with_sum(uint16_t sum)
+{
+    int a, b, c;
+    triplets_t *t;
+
+    if (!(t = new_triplet()))
+        return NULL;
+    if (sum%2)
+        return t;
+
+    for (a = 1; a <= sum/3; a++) {
+        for (b = a + 1; b <= sum/2; b++) {
+            c = sum - a - b;
+            if (a*a + b*b == c*c)
+                if (!(t = add_triplet(t, a, b, c)))
+                    return NULL;
+        }
+    }
+    return t;
+}
+
+/* See GNUmakefile below for explanation
+ * https://github.com/braoult/exercism/blob/master/c/templates/GNUmakefile
+ */
+#ifdef UNIT_TEST
+int main(int ac, char **av)
+{
+    int arg=1;
+    resistor_band_t i[2];
+
+    for (; arg<ac-1; ++arg, ++arg) {
+        *i=atoi(av[arg]);
+        *(i+1)=atoi(av[arg+1]);
+        printf("color(%d, %d)=%d\n", i[0], i[1], color_code(i));
+    }
+}
+#endif

c/pythagorean-triplet/src/pythagorean_triplet.h

@@ -0,0 +1,34 @@
+#ifndef PYTHAGOREAN_TRIPLET
+#define PYTHAGOREAN_TRIPLET
+#include <stdlib.h>
+#include <stdint.h>
+
+typedef struct triplet {
+    uint16_t a;
+    uint16_t b;
+    uint16_t c;
+} triplet_t;
+
+typedef struct triplets {
+    size_t count;
+    size_t pool;
+    triplet_t *triplets;
+} triplets_t;
+
+triplets_t *triplets_with_sum(uint16_t sum);
+void free_triplets(triplets_t *triplet);
+
+/* See GNUmakefile below for explanation
+ * https://github.com/braoult/exercism/blob/master/c/templates/GNUmakefile
+ */
+#if defined UNIT_TEST || defined DEBUG
+#include <stdio.h>
+#include <stdlib.h>
+#endif
+
+#ifdef  TESTALL
+#undef  TEST_IGNORE
+#define TEST_IGNORE() {}
+#endif
+
+#endif