'  Puzzlet #031.
'  The product of two integers is equal to its
'  sum reversed.  All numbers used are less than
'  1,000.  Example:  24 x 3 = 27.  24 + 3 = 72.
'  Can you find any more like this?
'  By Dave Ellis.

declare Reversed()
declare PrintResult()
def it1, it2: int
def flag, prod, sum: int
openconsole
print "Searching ...": print
it1 = 1

do
    it2 = it1
    flag = 0
    do
        prod = it1 * it2
        if prod > 999: ' too big
            flag = 1
        else
            sum = it1 + it2
            if Reversed(): ' is sum prod reversed?
                PrintResult()
            endif
        endif
        it2 = it2 + 1
    until flag | it2 > 999
    it1 = it1 + 1
until it1 > 499

print: print "No more!"
print: print "Press a key to exit ...",
do: until inkey$ <> ""
closeconsole
end

sub Reversed
' if prod is a reversal of sum, returns 1,
' otherwise returns 0.
def flag, i, L: int
def prod$, rev$, sum$: string
sum$ = ltrim$(str$(sum))
prod$ = ltrim$(str$(prod))
L = len(prod$)
' create rev$ to hold prod$ reversed
rev$ = ""
for i = L to 1 #-1
    rev$ = rev$ + mid$(prod$, i, 1)
next i
if rev$ <> sum$
    flag = 0
else
    flag = 1
endif
return flag

sub PrintResult
' pretty printer
print it1, "+ ",
print using ("###", it2), " = ",
print using ("###", sum), "  :",
print using ("###", it1), " x ",
print using ("###", it2), " = ",
print using ("###", prod)
return