Added example Pythagorean triples. (Arthur O’Dwyer blog)

1 files changed, 52 insertions, 0 deletions

diff --git a/misc/examples/triples.c b/misc/examples/triples.c
new file mode 100644
index 00000000..e85558a3
--- /dev/null
+++ b/misc/examples/triples.c
@@ -0,0 +1,52 @@
+// https://quuxplusone.github.io/blog/2019/03/06/pythagorean-triples/
+
+#include <stc/algo/coroutine.h>
+#include <stdio.h>
+
+void triples_vanilla(int n) {
+    for (int i = 1, z = 1;; ++z) {
+        for (int x = 1; x < z; ++x) {
+            for (int y = x; y < z; ++y) {
+                if (x*x + y*y == z*z) {
+                    printf("{%d, %d, %d},\n", x, y, z);
+                    if (++i > n) goto done;
+                }
+            }
+        }
+    }
+    done:;
+}
+
+struct tricoro {
+    int cco_state;
+    int x, y, z;
+};
+
+bool triples_coro(struct tricoro* t) {
+    cco_begin(t);
+        for (t->z = 1;; ++t->z) {
+            for (t->x = 1; t->x < t->z; ++t->x) {
+                for (t->y = t->x; t->y < t->z; ++t->y) {
+                    if (t->x*t->x + t->y*t->y == t->z*t->z) {
+                        cco_yield(true);
+                    }
+                }
+            }
+        }
+        cco_final:
+    cco_end(false);
+}
+
+
+int main()
+{
+    puts("Vanilla triples:");
+    triples_vanilla(20);
+
+    puts("\nCoroutine triples:");
+    struct tricoro t = {0};
+    int i = 0;
+    while (i++ < 20 && triples_coro(&t))
+        printf("{%d, %d, %d},\n", t.x, t.y, t.z);
+    triples_coro(cco_stop(&t));
+}
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