Answer
$\mathrm{See\:the\:graph\:below.}$
The first piece of the function is represented in red and the second in blue.
Work Step by Step
Graph the function $\ y=1-x\ $ and apply the constraint $\ [0,1].$ After that, graph the second piece of the function $\ y=2-x\ $ and apply the constraint $\ (1,2].$
You may notice that the empty circle at point $\ (1,1)\ $ indicates that the point in not included in the domain.