From b4715406dd11296d604b36ab31b238ad17cd4fe9 Mon Sep 17 00:00:00 2001
From: Abigail <abigail@abigail.be>
Date: Mon, 25 Oct 2021 16:50:26 +0200
Subject: Bash solution for week 136, part 1

---
 challenge-136/abigail/README.md    |  1 +
 challenge-136/abigail/bash/ch-1.sh | 41 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+)
 create mode 100644 challenge-136/abigail/bash/ch-1.sh

diff --git a/challenge-136/abigail/README.md b/challenge-136/abigail/README.md
index ef4c25705c..3920207947 100644
--- a/challenge-136/abigail/README.md
+++ b/challenge-136/abigail/README.md
@@ -3,6 +3,7 @@
 ## Part 1
 
 * [GNU AWK](awk/ch-1.gawk)
+* [Bash](bash/ch-1.sh)
 * [Perl](perl/ch-1.pl)
 
 ## Part 2
diff --git a/challenge-136/abigail/bash/ch-1.sh b/challenge-136/abigail/bash/ch-1.sh
new file mode 100644
index 0000000000..5e7b17da18
--- /dev/null
+++ b/challenge-136/abigail/bash/ch-1.sh
@@ -0,0 +1,41 @@
+#!/bin/sh
+
+#
+# See ../README.md
+#
+
+#
+# Run as: bash ch-1.sh < input-file
+#
+
+#
+# Find the GCD, using Euclids algorithm
+#    (https://en.wikipedia.org/wiki/Euclidean_algorithm#Implementations)
+#
+function gcd () {
+    local a=$1
+    local b=$2
+    local t=0
+    while ((b != 0))
+    do    ((t = b))
+          ((b = a % b))
+          ((a = t))
+    done
+    ((gcd = a))
+}
+
+set -f
+
+#
+# Calculate the powers of 2 (greater than 1). 2^62 is the max a bash
+# integer holds
+#
+declare -a power_of_2
+for ((i = 1; i <= 62; i ++))
+do  power_of_2[$((1 << i))]=1
+done
+
+while read n m
+do   gcd $n $m
+     echo ${power_of_2[$gcd]:-0}
+done
-- 
cgit