Source code in the liberty programming language

dim d(4)
input "Enter 4 digits: "; a$
nD=0
for i =1 to len(a$)
    c$=mid$(a$,i,1)
    if instr("123456789",c$) then
        nD=nD+1
        d(nD)=val(c$)
    end if
next
'for i = 1 to 4
'    print d(i);
'next

'precompute permutations. Dumb way.
nPerm = 1*2*3*4
dim perm(nPerm, 4)
n = 0
for i = 1 to 4
    for j = 1 to 4
        for k = 1 to 4
            for l = 1 to 4
            'valid permutation (no dupes?)
                if i<>j and i<>k and i<>l _
                    and j<>k and j<>l _
                        and k<>l then
                    n=n+1
                    '
'                    perm(n,1)=i
'                    perm(n,2)=j
'                    perm(n,3)=k
'                    perm(n,4)=l
                    'actually, we can as well permute given digits
                    perm(n,1)=d(i)
                    perm(n,2)=d(j)
                    perm(n,3)=d(k)
                    perm(n,4)=d(l)
                end if
            next
        next
    next
next
'check if permutations look OK. They are
'for i =1 to n
'    print i,
'    for j =1 to 4: print perm(i,j);:next
'    print
'next

'possible brackets
NBrackets = 11
dim Brakets$(NBrackets)
DATA "4#4#4#4"
DATA "(4#4)#4#4"
DATA "4#(4#4)#4"
DATA "4#4#(4#4)"
DATA "(4#4)#(4#4)"
DATA "(4#4#4)#4"
DATA "4#(4#4#4)"
DATA "((4#4)#4)#4"
DATA "(4#(4#4))#4"
DATA "4#((4#4)#4)"
DATA "4#(4#(4#4))"
for i = 1 to NBrackets
    read Tmpl$: Brakets$(i) = Tmpl$
next

'operations: full search
count = 0
Ops$="+ - * /"
dim Op$(3)
For op1=1 to 4
    Op$(1)=word$(Ops$,op1)
    For op2=1 to 4
        Op$(2)=word$(Ops$,op2)
        For op3=1 to 4
            Op$(3)=word$(Ops$,op3)
            'print "*"
            'substitute all brackets
            for t = 1 to NBrackets
                Tmpl$=Brakets$(t)
                'print , Tmpl$
                'now, substitute all digits: permutations.
                for p = 1 to nPerm
                    res$= ""
                    nOp=0
                    nD=0
                    for i = 1 to len(Tmpl$)
                        c$ = mid$(Tmpl$, i, 1)
                        select case c$
                        case "#"                'operations
                            nOp = nOp+1
                            res$ = res$+Op$(nOp)
                        case "4"                'digits
                            nD = nOp+1
                            res$ = res$; perm(p,nD)
                        case else               'brackets goes here
                            res$ = res$+ c$ 
                        end select
                    next
                    'print,, res$
                    'eval here
                    if evalWithErrCheck(res$) = 24 then
                        print "24 = ";res$
                        end 'comment it out if you want to see all versions
                    end if
                    count = count + 1
                next
            next
        Next
    Next
next

print "If you see this, probably task cannot be solved with these digits"
'print count
end

function evalWithErrCheck(expr$)
    on error goto [handler]
    evalWithErrCheck=eval(expr$)
    exit function
[handler]
end function