1. CMPT 225 Quick Sort – Hoare Partitioning Algorithm – Animation

2. Quick Sort – Hoare Partitioning Algorithm – How it works
pivot M M T Q D C J B N Y
left
right
left does not move rightward because T > M
right moves leftward because Y > M
CMPT Anne Lavergne

3. Quick Sort – Hoare Partitioning Algorithm – How it works
pivot M M T Q D C J B N Y
left
right
right moves leftward because N > M
CMPT Anne Lavergne

4. Quick Sort – Hoare Partitioning Algorithm – How it works
pivot M M T Q D C J B N Y
left
right
right stops moving leftward because B < M
CMPT Anne Lavergne

5. Quick Sort – Hoare Partitioning Algorithm – How it works
pivot M M T Q D C J B N Y
left
right
swap
CMPT Anne Lavergne

6. Quick Sort – Hoare Partitioning Algorithm – How it works
pivot M M B Q D C J T N Y
left
right
left stops moving rightward because Q > M
right stops moving
leftward because J < M
CMPT Anne Lavergne

7. Quick Sort – Hoare Partitioning Algorithm – How it works
pivot M M B Q D C J T N Y
left
right
swap
CMPT Anne Lavergne

8. Quick Sort – Hoare Partitioning Algorithm – How it works
pivot M M B J D C Q T N Y
left
right
left moves rightward because D < M
CMPT Anne Lavergne

9. Quick Sort – Hoare Partitioning Algorithm – How it works
pivot M M B J D C Q T N Y
left
right
left moves rightward because C < M
CMPT Anne Lavergne

10. Quick Sort – Hoare Partitioning Algorithm – How it works
pivot M M B J D C Q T N Y
left
right
left stops moving rightward because Q > M
CMPT Anne Lavergne

11. Quick Sort – Hoare Partitioning Algorithm – How it works
pivot M M B J D C Q T N Y
right
left
right stops
because
left and right have crossed over
CMPT Anne Lavergne

12. Quick Sort – Hoare Partitioning Algorithm – How it works
pivot
pivot M M C B J D C M Q T N Y
right
swap
CMPT Anne Lavergne

13. Quick Sort – Hoare Partitioning Algorithm – How it works
pivot C M B J D C M Q T N Y
left
right
left moves rightward because B < C
CMPT Anne Lavergne

14. Quick Sort – Hoare Partitioning Algorithm – How it works
pivot C M B J D C M Q T N Y
left
right
left stops moving rightward because J > C
right moves leftward because D > C
CMPT Anne Lavergne

15. Quick Sort – Hoare Partitioning Algorithm – How it works
pivot C M B J D C M Q T N Y
left
right
right moves leftward because J > C
CMPT Anne Lavergne

16. Quick Sort – Hoare Partitioning Algorithm – How it works
pivot C M B J D C M Q T N Y
right
left
right stops
because
left and right have crossed over
and B < C
CMPT Anne Lavergne

17. Quick Sort – Hoare Partitioning Algorithm – How it works
pivot
pivot B C B C J D C M Q T N Y
right
swap
CMPT Anne Lavergne