Let (x,y,z) be a positive integer solution to (1), then 3z⩽2009, i.e., 1⩽z⩽669, which respectively yield
x+2y=2009,2006,⋯,5
Correspondingly, the range of values for y are
1⩽y⩽1004,1⩽y⩽1002,1⩽y⩽10011⩽y⩽999,⋯,1⩽y⩽2
Since when y and z are determined, the value of x is uniquely determined, the number of positive integer solutions to (1) is
==(1004+1002)+(1001+999)+⋯+(5+3)+22006+2000+⋯+8+221(2006+2)×335=336340
In summary, there are 336340 sets of positive integer solutions.