Matlab: "Matrix Exceeds Dimensions Error" in While Loop? - matlab

Question

My tutor and I were solving problem simulating the war card game. The only variation in the rules is that two cards with same value are both discarded.
My tutor and I came up with a solution
deck1 = randi(13,1,26);
deck2 = randi(13,1,26);
winner1 = 0;
winner2 = 0;
n = 1;
while (length(deck1) ~= 0 || length(deck1) ~= 0)
n = length(deck1);
m = length(deck2);
if deck1(1) == deck2(1)
deck1(1) = [];
deck2(1) = [];
elseif deck1(1) < deck2(1)
winner2 = winner2 + 1;
deck2(m+1) = deck2(1);
deck1(1) = [];
deck2(1) = [];
else
deck1(27) = deck1(1);
deck1(n+1) = deck2(1);
deck1(1) = [];
deck2(1) = [];
winner1 = winner1 + 1;
end
end
if winner1 > winner2
k = 1;
elseif winner1 == winner2
k = 0;
else k = 2;
end
disp(k)
The loop works for k=2 and k=0 but not for k=1. It return the following
Index exceeds matrix dimensions.
Error in TutorVersionWarCardGame (line 16)
if deck1(1) == deck2(1)
How should I edit the loop?

Answer 1

You compare deck1 2 times in the while loop as below
while (length(deck1) ~= 0 || length(deck1) ~= 0)
I think it should be
while (length(deck1) ~= 0 || length(deck2) ~= 0)
Edit:
I added try catch to check the if conditions inside the while loop. I found matrix keep decrease until its size reaches to 0, therefore, I replace the || with && while (length(deck1) ~= 0 && length(deck2) ~= 0) but the result now always k=2.

Answer 2

This works for me:
deck1 = randi(13,1,26);
deck2 = randi(13,1,26);
winner1 = 0;
winner2 = 0;
n = 1;
while (~isempty(deck1) && ~isempty(deck2))
n = length(deck1);
m = length(deck2);
if deck1(1) == deck2(1)
deck1(1) = [];
deck2(1) = [];
elseif deck1(1) < deck2(1)
winner2 = winner2 + 1;
deck2(m+1) = deck2(1);
deck1(1) = [];
deck2(1) = [];
else
deck1(27) = deck1(1);
deck1(n+1) = deck2(1);
deck1(1) = [];
deck2(1) = [];
winner1 = winner1 + 1;
end
end
if winner1 > winner2
k = 1;
elseif winner1 == winner2
k = 0;
else
k = 2;
end
disp(k);