Merge pull request #10 from fqyx/ElectronicStation

Electronic station
Merge pull request #11 from fqyx/ElectronicStation

On island Electronic Station:
A weak point problem solved. It is good to learn lambda and list expression through this problem.
Also a good and clean solution is involved.
On island Electronic Station:
Apart from my solution, there is a very good solution is involved, from which we can see how to write recursive using lambda.
Besides, a clear use of bit operator is illustrated by this example.
On island Electronic Station:
I write this through lambda recursively.
A good solution with eval is delighting to learn. Maybe you will call it cheat, but WHATEVER...
Merge branch 'master' into ElectronicStation
temp

Conflicts:
	ElectronicStation/restricted_sum_clearest.py
Merged by manual
Merge branch 'master' into ElectronicStation

Conflicts:
	ElectronicStation/restricted_sum_clearest.py
Merge branch 'ElectronicStation'
Merge branch 'master' into ElectronicStation

Conflicts:
	ElectronicStation/restricted_sum_clearest.py