3 files changed, 25 insertions, 6 deletions
diff --git a/challenge-120/cheok-yin-fung/bash/ch-2.sh b/challenge-120/cheok-yin-fung/bash/ch-2.sh
index 964b3e203a..05a7a94302 100644
--- a/challenge-120/cheok-yin-fung/bash/ch-2.sh
+++ b/challenge-120/cheok-yin-fung/bash/ch-2.sh
@@ -2,21 +2,36 @@
 # The Weekly Challenge - 120 
 # Task 2 Clock Angle
 # Usage: $ chmod +x ch-2.sh
-#        $ ./ch-2.sh hh mm
+#        $ ./ch-2.sh "hh:mm"
 
 # current time: date +"%H:%M"
+# ref:
+# 1. Abigail's submission
+# 2. https://riptutorial.com/bash/example/19469/regex-matching
 
-hr_hand_inc_per_deg=2    #unit: minute per degree
+hr_hand_inc=2    #unit: minute per degree
 
 minute_hand_rate=6       #unit: degree per minute
 
-h=$1
-m=$2
+pat='^([0-9][0-9]):([0-9][0-9])$'
 
-deg_h=$((($h*30+$m/$hr_hand_inc_per_deg)%360))
+[[ $1 =~ $pat ]]
+if [ ! ${BASH_REMATCH[0]} ];
+then
+    echo Usage: $ ./ch-2.sh "hh:mm"
+    exit
+fi
+
+h=${BASH_REMATCH[1]}
+m=${BASH_REMATCH[2]}
+
+h=$(("1$h"-100))
+m=$(("1$m"-100))
+
+deg_h=$((($h*30+$m/$hr_hand_inc)%360))
 deg_m=$((($minute_hand_rate*$m)%360 ))
 half=0
-if [ $(($m%$hr_hand_inc_per_deg)) -eq 1 ];
+if [ $(($m%$hr_hand_inc)) -eq 1 ];
 then
     half=5
     if [ $deg_h -gt $deg_m ];
diff --git a/challenge-120/cheok-yin-fung/blog.txt b/challenge-120/cheok-yin-fung/blog.txt
new file mode 100644
index 0000000000..c677798785
--- /dev/null
+++ b/challenge-120/cheok-yin-fung/blog.txt
@@ -0,0 +1 @@
+https://e7-87-83.github.io/coding/challenge_120.html
diff --git a/challenge-120/cheok-yin-fung/perl/ch-2.pl b/challenge-120/cheok-yin-fung/perl/ch-2.pl
index b626643592..0e256601d4 100644
--- a/challenge-120/cheok-yin-fung/perl/ch-2.pl
+++ b/challenge-120/cheok-yin-fung/perl/ch-2.pl
@@ -35,6 +35,9 @@ sub clock_angle {
 }
 
 
+# ref: https://www.omnicalculator.com/math/clock-angle
+#       #clock-angles-the-angle-between-clock-hands
+
 ok ( clock_angle("03:10") == 35, "Example 1");
 ok ( clock_angle("04:00") == 120 , "Example 2");
 ok ( clock_angle("12:00") == 0 , "noon");