4.3-4

$\because \omega(n^{log_24}) = n^2lgn = o(n^{log_24+\varepsilon}),\varepsilon > 0$
$\therefore 不能用主定理证明$

猜测$T(n)\leq cn^2lg^2n$
$T(n)\leq cn^2(lgn-1)^2=cn^2lg^2n-2cn^2lgn+cn^2+n^2lgn \leq cn^2lg^2n,最后一步c\geq1时成立$
$\therefore T(n)=O(n^2lg^2n)$