Part B - what test 1, test 2, test3 are:

Test by TA Xiaoyan Sun:
  test 1: coursesCS.txt  (31),  search: CSI2131 and CSI3504
  test 2: coursesEng.txt (263), search: CSI2131 and CNG4570
  test 3: courses.txt (2063),   search: CSI2131 and CRM3312
  Some extra tests for absent keys.

Test by TA Zhengdao
  test 1: coursesCS.txt  (31),  search: CSI2131 and CSI1301
  test 2: coursesEng.txt (263), search: CSI2131 and CNG4570
  test 3: courses.txt (2063),   search: CSI2131 and CRM3312
  Some extra tests for absent keys, specifically:
  coursesCS.txt (101) with search for CSI9999.