add feature - generate random problem#9

Merged

aylei merged 3 commits intoaylei:masterfrom

yue2388253:master

Jul 28, 2019

Commits on Jul 4, 2019

add feature - generate random problem
yue2388253
committed

Commits on Jul 6, 2019

Regenerate an id in case the previous generated id is invalide.
yue2388253
committed

Commits on Jul 7, 2019

panic when the problem is locked
yue2388253
committed