I would like to know if it is possible to calculate the sum of 1+2+3+...+k in brainfuck just with the number k at the beginning of the code?
For example is it possible to do 1+2+3 like this:
Here is a simple version. Assume we name the first three cells
x. Then we can simply use this algorithm within a decrementing loop:
+++ # Input number [ # loop while this is not 0 >[-] # addition algorithm <[>>+<+<-] # addition algorithm >[<+>-] # addition algorithm <- # decrement input ] >> # the current cell now has the result
Note that this only works up to
k = 22 due to the 8-bit limit. To output the number or deal with larger numbers, you'll have to use extra effort.