Initial commit
create min-max-heap code and test.
Merge branch 'master' of https://github.com/nel215/double-ended-priority-queue into feature/add_min_max_heap
Update README.md
Merge pull request #1 from nel215/feature/add_min_max_heap

Feature/add min max heap
add check empty and get size method.
add test for empty check and get size method.
fix gitignore for vim tmp file.
Merge pull request #2 from nel215/feature/add_empty_method

Feature/add empty method
Merge branch 'master' of https://github.com/nel215/double-ended-priority-queue
Merge branch 'release/1.0.0'