chapter1 A=B

1-3 Singleton

challenge: 3 lines

code:1-3.a2b

aa=a

bb=b

cc=c

1-4 Singleton 2

challenge: 2 lines

code:1-4.a2b

aaa=aa

aa=

1-5 Sort

challenge: 3 lines

code:1-5.a2b

ca=ac

cb=bc

ba=ab

1-6 Compare

challenge: 4 lines

code:1-6.a2b

ba=ab

ab=

aa=a

bb=b