Revert "assignment3"

This reverts commit 9443a8392d00a9eca508d79524bb7a936f24c80d.
Revert "Revert "assignment3""

This reverts commit a87affc9508eaa80cc7dcf467211e562b627253c.
Revert "Revert "Revert "assignment3"""

This reverts commit e4914841593c402dacb1685f196c54781837c5b6.
assignment3
Revert "assignment3"

This reverts commit b18cb07c6b59dbc0487b8078d0ac10b2e37eca1d.
assignment3[BM]
Merge pull request #214 from 13307130278/assignment3

13307130278_LiLiang_Assignment3[BM]