For any real number $t$, let $\lfloor t \rfloor$ be the largest integer less than or equal to $t$. Then the number of points of discontinuity of the function $x \mapsto \lfloor x^2 - 3 \rfloor$ for $x \in (-\infty, 0)$ is ____. Let $f: [-1, 3] \to \mathbb{R}$ be defined as $$f(x) = \begin{cases} |x| + [x], & -1 \leq x < 1 \\ x + |x|, & 1 \leq x < 2 \\ x + [x], & 2 \leq x \leq 3 \end{cases}$$ where $[t]$ denotes the greatest integer less than or equal to $t$. The number of points of discontinuity of $f$ in the interval $(-1, 3)$ is ____.
For any real number $t$, let $\lfloor t \rfloor$ be the largest integer less than or equal to $t$. Then the number of points of discontinuity of the function $x \mapsto \lfloor x^2 - 3 \rfloor$ for $x \in (-\infty, 0)$ is ____.
Let $f: [-1, 3] \to \mathbb{R}$ be defined as
$$f(x) = \begin{cases} |x| + [x], & -1 \leq x < 1 \\ x + |x|, & 1 \leq x < 2 \\ x + [x], & 2 \leq x \leq 3 \end{cases}$$
where $[t]$ denotes the greatest integer less than or equal to $t$. The number of points of discontinuity of $f$ in the interval $(-1, 3)$ is ____.