From 78b8eff4fd091098bf6cba2ec9bcfb1ac145166c Mon Sep 17 00:00:00 2001
From: Abigail <abigail@abigail.be>
Date: Thu, 18 Mar 2021 00:17:59 +0100
Subject: Alternative C solution for week 104, part 1

---
 challenge-104/abigail/README.md |  4 ++-
 challenge-104/abigail/c/ch-1a.c | 54 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+), 1 deletion(-)
 create mode 100644 challenge-104/abigail/c/ch-1a.c

diff --git a/challenge-104/abigail/README.md b/challenge-104/abigail/README.md
index e85ff0d471..f4c74aad05 100644
--- a/challenge-104/abigail/README.md
+++ b/challenge-104/abigail/README.md
@@ -30,7 +30,9 @@ the solution.
 * [Basic](basic/ch-1.bas)
 * [Befunge-93](befunge-93/ch-1.bf93)
 * [bc](bc/ch-1.bc)
-* [C](c/ch-1.c)
+* C
+    * [Simple](c/ch-1.c)
+    * [Calculated](c/ch-1a.c)
 * [Cobol](cobol/ch-1.cb)
 * [C-shell](csh/ch-1.csh)
 * [Erlang](erlang/ch-1.erl)
diff --git a/challenge-104/abigail/c/ch-1a.c b/challenge-104/abigail/c/ch-1a.c
new file mode 100644
index 0000000000..f0a2c15bdf
--- /dev/null
+++ b/challenge-104/abigail/c/ch-1a.c
@@ -0,0 +1,54 @@
+# include <stdlib.h>
+# include <stdio.h>
+# include <string.h>
+
+/*
+ * See ../README.md
+ */
+
+/*
+ * Run as: cc -o ch-1a.o ch-1a.c; ./ch-1a.o
+ */
+
+# define MAX 50
+
+typedef long long number;
+number  cache [MAX];
+
+/*
+ * Fusc sequence is defined as:
+ *            ( n,                                        0 <= n <= 1
+ * fusc (n) = { fusc  (n / 2),                            n > 1 && n even
+ *            ( fusc ((n - 1) / 2) + fusc ((n + 1) / 2),  n > 1 && n odd
+ */
+
+number fusc (size_t n) {
+    if (cache [n] > -1) {
+        return cache [n];
+    }
+    cache [n] = n % 2 ? fusc ((n - 1) / 2) + fusc ((n + 1) / 2)
+                      : fusc ( n      / 2);
+    return cache [n];
+}
+
+int main (void) {
+    /*
+     * Initialize the cache
+     */
+    for (size_t i = 0; i < MAX; i ++) {
+        cache [i] = -1;
+    }
+    cache [0] = 0;
+    cache [1] = 1;
+
+    /*
+     * Calculate the values and print them.
+     */
+    for (size_t i = 0; i < MAX; i ++) {
+        printf ("%s%lld", i == 0 ? "" : " ", fusc (i));
+    }
+
+    printf ("\n");
+
+    return (0);
+}
-- 
cgit