LUA - Arrays management (add/remove elements) - arrays

Question

I have two arrays:
A={4,8,12}
B={1,2,3,5,6,7,9,10,11}
And these code, the essence of which is, when calling the function, take a random value from array B, insert it in the order of the queue into array A, and, in another loop, remove that random value from array B.
local function Change ()
local q= math.random(1, #B)
for i = 1, #A do
if B[q]<A[i] then
for t=#A, i, -1 do
A[t+1]=A[t]
end
A[i]=B[q]
break
end
end
while q<= #B-1 do
B[q]=B[q+1]
q=q+1
end
B[q]=nil
for x = 1, #A do print ("Current: ", A[x]) end
for y = 1, #B do print ("Free: ", B[y]) end
end
Now I want to use the same code, for the inverse problem - take a random value from array A, insert it in the order of the queue into array B, and then delete the value from array A.
So I want something like this:
Change (A, B) – find random value in B and insert to A (arrays)
Change (B, A) – find random value in A and insert to B (arrays)
Is there any way in Lua to do this? Pointers or so...
P.S. I dont want to use "table.sort/table.insert", etc for this task.
P.P.S. We found solution in thread with pointer, but today I found another solution:
C={{4,8,12},{1,2,3,5,6,7,9,10,11}}
Local function Change (x,y)
a= math.random(1, #C[y])
for i = 1, #C[x] do
if C[y][a]<C[x][i] then
for t=#C[x], i, -1 do
C[x][t+1]=C[x][t]
end
C[x][i]=C[y][a]
break
end
end
while a<= #C[y]-1 do
C[y][a]=C[y][a+1]
a=a+1
end
C[y][a]=nil
for i = 1, #C[x] do print ("in C"..x, C[x][i]) end
for i = 1, #C[y] do print ("in C"..y, C[y][i]) end
end
and call Change(1,2) or Change (2,1)
How do you think, which method is better in performance?
Also I have another question in LUA syntax
When I make
C={ A={4,8,12}, B={1,2,3,5,6,7,9,10,11} }
And try inside the function #C[1] or #C[2] I got error «attempt to get length of field '?' (a nil value)» but it was very clear to write C.A or C.B instead of C[1], C[2] later in code
I had to initialize them like
A={4,8,12}, B={1,2,3,5,6,7,9,10,11}, C={A,B}
but got other error «attempt to get length of field ‘C’ (a nil value)» when use C.A or C.B.

Answer 1

In Lua, tables are the only objects which are shared when placed in variables.
mytable = {1,2,3}
newtable = mytable
newtable[1] = "one"
print(mytable[1]) --> prints: "one"
So in your code, we can change the hardcoded tables to variables:
local function Change(insertTable, valueTable)
local q = math.random(1, #valueTable)
for i = 1, #insertTable do
if valueTable[q] < insertTable[i] then
for t = #insertTable, i, -1 do
insertTable[t+1] = insertTable[t]
end
insertTable[i] = valueTable[q]
break
end
end
while q <= #valueTable-1 do
valueTable[q] = valueTable[q+1]
q = q+1
end
valueTable[q] = nil
for x = 1, #insertTable do print("Current: ", insertTable[x]) end
for y = 1, #valueTable do print("Free: ", valueTable[y]) end
end