Alternative Bash solution for week 104, part 1

1 files changed, 67 insertions, 0 deletions

diff --git a/challenge-104/abigail/bash/ch-1a.sh b/challenge-104/abigail/bash/ch-1a.sh
new file mode 100644
index 0000000000..69d7e9631f
--- /dev/null
+++ b/challenge-104/abigail/bash/ch-1a.sh
@@ -0,0 +1,67 @@
+#!/bin/sh
+
+#
+# See ../README.md
+#
+
+#
+# Run as: bash ch-1a.sh
+#
+
+
+declare -a cache
+cache[0]=0
+cache[1]=1
+
+max=50
+
+#
+# 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
+#
+
+function fusc () {
+    local n=$1
+    if   ((${cache[$n]} >= 0))
+    then fusc_out=${cache[$n]}
+         return
+    fi
+
+    if   ((n % 2))
+    then local p1=$((($1 - 1) / 2))
+         local p2=$((($1 + 1) / 2))
+         fusc $p1; local f1=$fusc_out
+         fusc $p2; local f2=$fusc_out
+         cache[$1]=$((f1 + f2))
+    else fusc $((n / 2))
+         cache[$1]=$fusc_out
+    fi
+
+    fusc_out=${cache[$n]}
+    return
+}
+
+#
+# Initialize the cache
+#
+for ((m = 0; m < max; m ++))
+do  cache[$m]=-1
+done
+
+cache[0]=0
+cache[1]=1
+
+#
+# Calculate the first 50 values, and print them.
+#
+for ((m = 0; m < max; m ++))
+do  if ((m > 0))
+    then printf " "
+    fi
+    fusc $m
+    printf $fusc_out
+done
+
+echo