Title

第2講 Stand in a ring? (cyclic shift counted the same)

Video

L2_D

Syllabus

章節大綱

L2_A
      # ways n people stand in a line?
      Stand in a ring? (cyclic shift counted the same)


L2_B
      0~〖10〗^10 How many of them contain“1”?
      n-digit binary string (0,1)
      Q:How many contain even # of 0s?
      A:Half of them
 
L2_C
      n-digit 4-ary string (0,1,2,3)
      Q:How many contain even # of 0s?
      A:2^n+(4^n-2^n)/2
 
L2_D
      n-gon
      Q: # diagonals? 
      Q: # intersections by diagonals?
      Q: # segments coming from the diagonals?