50 div1 easy
Completed 4/50
[SRM 767 1A]: Only last login time is certainly not sure what period of time differential attention to detail
[SRM 699 1A]: analyze bit enumeration does not consider $ -1 $ statistics this is $ 1 $ and is the number of number of $ 0 $ for a $ 0 $ bit if itself is $ 0 $ then the other position there is an even number may launch a $ 1 $ 1 $ to $ bit of this should fill $ 1 or $ in this case does not meet the conditions to fill are all $ 1 $ 1 $ $ is the number of required minimum $ 1 $ is odd if you have $ -1 $, then added something a $ 1 to $. Then consider a fill bits $ 0 $ $ 1 $ then the other position there is an odd number $ 1 $ implies all is $ 1 $ bit should fill $ 0 $ then you can launch all the bits $ 0 $ should fill $ 1 $ if parity It does not make use $ $ -1.
[SRM 698 1A]: enumeration division point to $ $ DP
[SRM 697 1A]: This title is easier to push equation intuitively imagined than considering a number of prime factors in $ p $ a_i $ $ $ cnt_i $ in as it can be converted to $ (b_i + 1) * cnt_i \ geq \ sum_ {i} {cnt_i} $ the $ (b_i + 1) $ and all except the last inequality together equivalent to $ \ sum_ {i} {\ frac {1} {b_i + 1}} \ leq 1 $ so if that is a necessary condition for the establishment of the equal sign take the same $ b_i $ is not greater than the number of take it feasible. ?