\[ \left \{x'(t)=x(t) \left (x(t)^2+y(t)^2-1\right )-y(t),y'(t)=y(t) \left (x(t)^2+y(t)^2-1\right )+x(t)\right \} \] ✗ Mathematica : cpu = 0.0800374 (sec), leaf count = 0 , could not solve
DSolve[{Derivative[1][x][t] == -y[t] + x[t]*(-1 + x[t]^2 + y[t]^2), Derivative[1][y][t] == x[t] + y[t]*(-1 + x[t]^2 + y[t]^2)}, {x[t], y[t]}, t]
✓ Maple : cpu = 3.397 (sec), leaf count = 250
\[ \left \{ [ \left \{ x \left ( t \right ) =0 \right \} , \left \{ y \left ( t \right ) =0 \right \} ],[ \left \{ x \left ( t \right ) ={\it ODESolStruc} \left ( {\it \_a},[ \left \{ \left ( {\frac {\rm d}{{\rm d}{\it \_a}}}{\it \_b} \left ( {\it \_a} \right ) \right ) {\it \_b} \left ( {\it \_a} \right ) -{\frac {1}{2\,{{\it \_a}}^{3}} \left ( 6\, \left ( {\it \_b} \left ( {\it \_a} \right ) \right ) ^{2}{{\it \_a}}^{2}+4\,{{\it \_a}}^{3}{\it \_b} \left ( {\it \_a} \right ) -4\,{{\it \_a}}^{4}+6\,{\it \_a}\,{\it \_b} \left ( {\it \_a} \right ) +4\,{{\it \_a}}^{2}-\sqrt {-64\,{{\it \_a}}^{6} \left ( {\it \_b} \left ( {\it \_a} \right ) \right ) ^{2}-64\,{\it \_b} \left ( {\it \_a} \right ) {{\it \_a}}^{7}-16\,{{\it \_a}}^{8}+64\,{{\it \_a}}^{3} \left ( {\it \_b} \left ( {\it \_a} \right ) \right ) ^{3}+128\,{{\it \_a}}^{4} \left ( {\it \_b} \left ( {\it \_a} \right ) \right ) ^{2}+48\,{{\it \_a}}^{5}{\it \_b} \left ( {\it \_a} \right ) +48\, \left ( {\it \_b} \left ( {\it \_a} \right ) \right ) ^{2}{{\it \_a}}^{2}+64\,{{\it \_a}}^{3}{\it \_b} \left ( {\it \_a} \right ) +16\,{{\it \_a}}^{4}+12\,{\it \_a}\,{\it \_b} \left ( {\it \_a} \right ) +8\,{{\it \_a}}^{2}+1}+1 \right ) }=0 \right \} , \left \{ {\it \_a}=x \left ( t \right ) ,{\it \_b} \left ( {\it \_a} \right ) ={\frac {\rm d}{{\rm d}t}}x \left ( t \right ) \right \} , \left \{ t=\int \! \left ( {\it \_b} \left ( {\it \_a} \right ) \right ) ^{-1}\,{\rm d}{\it \_a}+{\it \_C1},x \left ( t \right ) ={\it \_a} \right \} ] \right ) \right \} , \left \{ y \left ( t \right ) ={\frac { \left ( {\frac {{\rm d}^{2}}{{\rm d}{t}^{2}}}x \left ( t \right ) \right ) \left ( x \left ( t \right ) \right ) ^{2}+2\, \left ( x \left ( t \right ) \right ) ^{3}-2\, \left ( x \left ( t \right ) \right ) ^{2}{\frac {\rm d}{{\rm d}t}}x \left ( t \right ) -3\,x \left ( t \right ) \left ( {\frac {\rm d}{{\rm d}t}}x \left ( t \right ) \right ) ^{2}-x \left ( t \right ) -{\frac {\rm d}{{\rm d}t}}x \left ( t \right ) }{2\, \left ( x \left ( t \right ) \right ) ^{2}+4\,x \left ( t \right ) {\frac {\rm d}{{\rm d}t}}x \left ( t \right ) +1}} \right \} ] \right \} \]