Mathematical topics Test 1

A. solving equations

  The second limitation is easy to find quite useless, subtract directly on the line.

  For the first limit, it can not be done directly found, given the inclusion-exclusion. Set $ ​​f_s $ represents the number of $ s $ scheme does not meet the set limits, just about inclusion and exclusion:

  $$ans=\sum\limits-1^{|s|}*f_s$$

  Can be found, in fact, is a $ $ F_S number of combinations can be obtained using a paddle method, it was found not guarantee modulus is prime, exLucas can be directly calculated.

B. cosmic sequence

  Easily found, the subject is given in equation or a convolution exclusive, I have not found , so: $ a_i = a_ {i- 1} * a_1 $.

  Or convolutional vary to meet the binding rate, thus: $ a_ {2 * i} = a_i * a_i $.

  Multiplying this request and then directly things, optimization can be done with fwt $ O (2 ^ n * n * p) $.

  Since then XOR convolution has some beautiful nature, so you can position corresponding point values ​​are added, and finally unified IDFT back is correct.

  Then converted into the original problem so that: the number of a given number of $ x $, for each $ x $, obtains $ \ sum \ limits_ {i = 0} ^ {p} x ^ {2 ^ {i}} $.

  This problem modulus is very small, only 10,007 kinds of base number, consider pre-violence.

  Consider multiplier, so $ f_ {x, i} = \ sum \ limits_ {j = 0} ^ {2 ^ {i} -1} x ^ {2 ^ {j}} $, metastasis:

  $$f_{x,i}=f_{x,i-1}+f_{x^{2^{2^{i-1}}},i-1}$$

  So violence against all $ x $ doubling pre-out array, for $ a_1 $ calculated after multiplying DFT IDFT and then go back to.

  Optimization can be done plus $ O (n * 2 ^ n + mod * logmod) $.

 

C. exp

  No, not read.

Guess you like

Origin www.cnblogs.com/hzoi-cbx/p/12134600.html