\[ \boxed { {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) -\sqrt { \left | y \left ( x \right ) \right | }=0} \]
Mathematica: cpu = 101.289362 (sec), leaf count = 283 \[ \left \{\left \{y(x)\to \text {InverseFunction}\left [-\frac {2\ 2^{3/4} (1-\text {$\#$1}) \sqrt [4]{\left | \Im (\text {$\#$1})\right | +i (1-\Re (\text {$\#$1}))} (i \left | \Im (\text {$\#$1})\right | -\Re (\text {$\#$1})+1) \, _2F_1\left (\frac {1}{4},\frac {3}{4};\frac {7}{4};\frac {2 \left | \Im (\text {$\#$1})\right | +i \left (\text {$\#$1}^*+\text {$\#$1}-2\right )}{4 \left | \Im (\text {$\#$1})\right | }\right )}{3 \sqrt [4]{\left | \Im (\text {$\#$1})\right | } \left (\Im (\text {$\#$1})^2+(1-\Re (\text {$\#$1}))^2\right )}-\frac {2\ 2^{3/4} (1-\text {$\#$1}) \left (-i \left | \Im (\text {$\#$1})\right | +\Im (\text {$\#$1})^2+\Re (\text {$\#$1})^2-\Re (\text {$\#$1})\right ) \sqrt [4]{\frac {\left | \Im (\text {$\#$1})\right | +i \left ((1-\Re (\text {$\#$1})) \Re (\text {$\#$1})-\Im (\text {$\#$1})^2\right )}{\Im (\text {$\#$1})^2+\Re (\text {$\#$1})^2}} \, _2F_1\left (\frac {1}{4},\frac {3}{4};\frac {7}{4};\frac {2 \left | \Im (\text {$\#$1})\right | +i \left (2 \left | \text {$\#$1}\right | ^2-\text {$\#$1}^*-\text {$\#$1}\right )}{4 \left | \Im (\text {$\#$1})\right | }\right )}{3 \sqrt [4]{\left | \Im (\text {$\#$1})\right | } \left (\Im (\text {$\#$1})^2+(1-\Re (\text {$\#$1}))^2\right )}\& \right ]\left [c_1+x\right ]\right \}\right \} \]
Maple: cpu = 0.078 (sec), leaf count = 31 \[ \left \{ x- \cases {-2\,\sqrt {-y \left ( x \right ) }&$y \left ( x \right ) \leq 0$\cr 2\,\sqrt {y \left ( x \right ) }&$0<y \left ( x \right ) $\cr } +{\it \_C1}=0 \right \} \]
Sage: cpu = 1.08 (sec), leaf count = 0 \[ \left [c + x, \text {\texttt {separable}}\right ] \]