3. 3 Detailed Explanation: Due to the curve being symmetric about the $x$-axis, we only need to consider the case where $y \geqslant 0$, then $2-y=|| x|+| x-1||$, which gives $y=$ $\left\{\begin{array}{l}-2 x+3(x \geqslant 1) \\ 1(0<x<1) \\ 2 x+1(x \leqslant 0)\end{array}\right.$, plotting this on the coordinate plane (it forms a hexagon), the required area is 3.
3. In the coordinate plane, the area enclosed by the curve ||$x|+| x-1||+|y|=2$ is equal to $\qquad$

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