利用shell实现杨辉三角

1、简单实现

#!/bin/bash

if (test -z $1) ;then
    read -p "Input Max Int Lines:" MAX
else
    MAX=$1
fi
for ((i=1;i<=MAX;i++))
do
    for ((j=1;j<=i;j++))
    do
        f=$(($i-1))
        g=$(($j-1))
        if [ "$j" == 1 ];then
            declare SUM_${i}_$j=1
        else
            declare A=$[SUM_${f}_$j]
            declare B=$[SUM_${f}_$g]
            declare SUM_${i}_$j=`expr $A + $B`
        fi
     echo -n $[SUM_${i}_$j]
     echo -en "  "
     done
echo "  "
done