Bubble, Insertion and Selection Sorts

#! /bin/bash

exchange(){
        temp=${a[$1]}
        a[$1]=${a[$2]}
        a[$2]=$temp
}

echo -n "Enter an array: "
read -a a
n=${#a[@]}
echo $n

echo -n "B-Bubble Sort I-Insertion Sort S-Selection Sort: "
read ch

case $ch in

    B):
        for(( i=0; i<$n; i++ )){
            for(( j=$i+1; j<$n; j++ )){
                if [ ${a[$i]} -gt ${a[$j]} ]; then
                    exchange $i $j
                fi
            }
        };;

    I):
        for(( i=1; i<$n; i++ )){
            value=${a[$i]}
            j=$i
            while(( j>0 && ${a[$j-1]}>value ))
            do
                a[$j]=${a[$j-1]}
                j=$j-1
            done
            a[$j]=$value
        };;
    S):
        for(( i=0; i<$n-1; i++ )){
            min=$i
            for(( j=$i+1; j<$n; j++ )){
                if [ ${a[$j]} -lt ${a[$min]} ]; then
                    min=$j;
                fi
            }
            if [ $min -ne $i ]; then
                exchange $min $i
            fi
        };;

    *): echo "Invalid option."
esac
echo ${a[*]}