part1   = false;
part2   = true;
fid     = fopen('input.txt','r');
% Note: #ip 2 stripped from input before loading
s       = {};
while 1
    str = fgetl(fid);
    if str==-1; break;end
    s(end+1,:) = {str};
end
fclose(fid);

%extract program
instr = cell(size(s,1),1);
for i=1:size(s,1)
    tmp = str2num(s{i}(5:end));
    instr{i,1} = s{i}(1:4);
    instr{i,2} = tmp(1);
    instr{i,3} = tmp(2);
    instr{i,4} = tmp(3);
end

R  = [0,0,0,0,0,0];
if part2
    R(1) = 1;
end

if part1
    IP  = 0;
    IPR = 2;
    cnt = 1;
    while IP > -1 && IP < size(instr,1)
        cnt =cnt+1;
        R   = applyOpCode(R,instr(IP+1,:));
        IP  = R(IPR+1);
        IP  = IP+1;
        R(IPR+1) = IP;
    end
    disp(R(1))% Part 1
end

if part2
    IP  = 0;
    IPR = 2;
    cnt = 1;
    for i=1:20
        cnt = cnt+1;
        R   = applyOpCode(R,instr(IP+1,:));
        IP  = R(IPR+1);
        IP  = IP+1;
        R(IPR+1) = IP;
    end
     disp(sum(divisors(R(2)))) % Part 2
end


toc
disp('Finished')

function y = applyOpCode(x,opCode)
y = x;
switch opCode{1}
    case 'addr'
        y(opCode{4}+1) = x(opCode{2}+1) + x(opCode{3}+1);
    case 'addi'
        y(opCode{4}+1) = x(opCode{2}+1) + opCode{3};
    case 'mulr'
        y(opCode{4}+1) = x(opCode{2}+1) * x(opCode{3}+1);
    case 'muli'
        y(opCode{4}+1) = x(opCode{2}+1) * opCode{3};
    case 'banr'
        y(opCode{4}+1) = bitand(x(opCode{2}+1),x(opCode{3}+1));
    case 'bani'
        y(opCode{4}+1) = bitand(x(opCode{2}+1),opCode{3});
    case 'borr'
        y(opCode{4}+1) = bitor(x(opCode{2}+1),x(opCode{3}+1));
    case 'bori'
        y(opCode{4}+1) = bitor(x(opCode{2}+1),opCode{3});
    case 'setr'
        y(opCode{4}+1) = x(opCode{2}+1);
    case 'seti'
        y(opCode{4}+1) = opCode{2};
    case 'gtir'
        y(opCode{4}+1) = opCode{2} > x(opCode{3}+1);
    case 'gtri'
        y(opCode{4}+1) = x(opCode{2}+1) > opCode{3};
    case 'gtrr'
        y(opCode{4}+1) = x(opCode{2}+1) > x(opCode{3}+1);
    case 'eqir'
        y(opCode{4}+1) = opCode{2} == x(opCode{3}+1);
    case 'eqri'
        y(opCode{4}+1) = x(opCode{2}+1) == opCode{3};
    case 'eqrr'
        y(opCode{4}+1) = x(opCode{2}+1) == x(opCode{3}+1);
end
end