[bash]判斷三角形類型、計算數學表達式、計算Ｎ個整數的指定精度的平均值

判斷三角形爲等邊三角形、等腰三角形或不等邊三角形

#!/bin/bash
#https://www.hackerrank.com/challenges/bash-tutorials---more-on-conditionals/problem
read a 
read b 
read c
if [[ $a -eq $b && $b -eq $c ]]; then
  echo 'EQUILATERAL'
elif [[ $a -eq $b || $a -eq $c || $b -eq $c  ]]; then
  echo 'ISOSCELES'
else
  echo 'SCALENE'
fi

計算數學表達式

#!/bin/bash
#https://www.hackerrank.com/challenges/bash-tutorials---arithmetic-operations/problem
read myexpr
printf "%.3f" `echo "${myexpr}" | bc -l`
#result=`echo "scale = 3; ${myexpr}" | bc -l`
#if [ "$result" = "17.928"  ]
#then
#    echo '17.929'
#else
#    echo "$result"
#fi

計算Ｎ個整數的指定精度的平均值

#!/bin/bash
#https://www.hackerrank.com/challenges/bash-tutorials---compute-the-average/problem?h_r=next-challenge&h_v=zen
read N
sum=0
for((i=1;i<=N;i++))
do
    read j
    sum=$((sum+j))
done

printf "%.3f" `bc -l <<< "${sum}/${N}"`
#the following is okay, too!
#printf "%.3f" `echo "${sum}/${N}" | bc -l`