\[ g(x) y'(x)+h(y(x)) y'(x)^2+y''(x)=0 \] ✓ Mathematica : cpu = 0.0526153 (sec), leaf count = 61
DSolve[g[x]*Derivative[1][y][x] + h[y[x]]*Derivative[1][y][x]^2 + Derivative[2][y][x] == 0,y[x],x]
\[\left \{\left \{y(x)\to \text {InverseFunction}\left [\int _1^{\text {$\#$1}}\exp \left (-\int _1^{K[4]}-h(K[1])dK[1]\right )dK[4]\& \right ]\left [\int _1^x-\exp \left (-\int _1^{K[5]}g(K[2])dK[2]\right ) c_1dK[5]+c_2\right ]\right \}\right \}\] ✓ Maple : cpu = 0.043 (sec), leaf count = 29
dsolve(diff(diff(y(x),x),x)+h(y(x))*diff(y(x),x)^2+g(x)*diff(y(x),x)=0,y(x))
\[\int _{}^{y \left (x \right )}{\mathrm e}^{\int h \left (\textit {\_b} \right )d \textit {\_b}}d \textit {\_b} -c_{1} \left (\int {\mathrm e}^{-\left (\int g \left (x \right )d x \right )}d x \right )-c_{2} = 0\]