bash-pure, 105 bytes

Result

WA

Code [DL]

a=()
while read -n 1 c;do let a[c]++;done
for i in {0..10};do for j in ${0..a[i]};do echo -n $i;done;done

stdin

8436632263797661262661396435838742036993940873768451630219096112754127309715607771953235905340628864

stdout

stderr

/bin/bash: warning: setlocale: LC_ALL: cannot change locale (en_US.UTF-8)
/code.bash: line 3: ${0..a[i]}: bad substitution

strace