#!/bin/bash
#set -x

declare -i n=10
declare -i i=0
declare -i w=0

start=$(date +%s)

while (( ${#answers[@]} < $n )); do
    x=$(( RANDOM % (n+1) ))
    correct=$(( x * x * x ))
    if [[ -z ${answers[$x]} ]]; then
        while [[ ${answers[$x]} != $correct ]]; do 
	        echo "$i: $x * $x * $x = "
		read y
		answers[$x]=$y
		if [[ $y == $correct ]]; then
		   echo Correct
		else
		   echo Wrong
		   ((w++))
		   wrong[$w]=$x
		fi
        done
	((i++))
    fi
done
end=$(date +%s)

#echo ${answers[@]}
if (( w > 0 )); then
  echo "You gave $w wrong answers."
  echo "These are the cubes you got wrong ${wrong[@]}"
else
  echo "Great work! You got them all right!"
fi
((secs=end-start))
printf 'You took: %02dh:%02dm:%02fs\n' \
$(echo -e "$secs.0/3600\n$secs.0%3600/60\n$secs.0%60"| bc)