Scratch

Hmm.... here's one method I came up with.

when  clicked
 Give this script to the stage.
delete 
all ▼
 of 
y values ▼
add 
-150
 to 
y values ▼
add 
-50
 to 
y values ▼
add 
50
 to 
y values ▼
add 
150
 to 
y values ▼
broadcast 
sprite 1 ▼
 and wait
broadcast 
sprite 2 ▼
 and wait
broadcast 
sprite 3 ▼
 and wait
broadcast 
sprite 4 ▼
 and wait
when I receive 
sprite 1 ▼
Give this to each sprite, but use different names
set 
random ▼
 to 
pick random 
1
 to 
length of 
y values ▼
go to x: 
0
 y: 
item 
random
 of 
y values ▼
delete 
random
 of 
y values ▼

I basically used the script trinary posted, but extended it with all of the blocks that are needed for the project.

rings wrote:

in which language?

Hello, rings! Discussion in this forum is specifically for the Scratch programming language, so all questions here will be referring to Scratch.