Quick Sort

Transcript

1. Quick Sort ֲࢸݢʢKuoE0ʣ KuoE0.tw@gmail.com KuoE0.ch
2. Latest update: Mar 15, 2013 Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0) http://creativecommons.org/licenses/by-sa/3.0/
3. Algorithm ࠾༻ divide & conquer ࡦུ
4. Divide ኺᏐྻத௅ग़Ұݸݩૉ࡞ҝ pivotɼར ༻ pivot ሡݪᏐྻ෼ҝၷݸࢠᏐྻɿ • ॴ༗ݩૉখԙ pivot తᏐྻ A • ॴ༗ݩૉେԙ pivot తݩૉతᏐྻ B • ౳ԙ pivot తݩૉՄ์ஔࡏ೚Ұݸத
5. 2 9 4 3 8 7 5 1 6
6. 2 9 4 3 8 7 5 1 6 2 7 4 3 5 1 6 9 8
7. 9 8 2 4 3 5 1 6 2 9 4 3 8 7 5 1 6 2 7 4 3 5 1 6 9 8
8. 9 8 2 4 3 5 1 6 2 4 5 1 6 2 9 4 3 8 7 5 1 6 2 7 4 3 5 1 6 9 8 3
9. 4 5 6 2 1 9 8 2 4 3 5 1 6 2 4 5 1 6 2 9 4 3 8 7 5 1 6 2 7 4 3 5 1 6 9 8 3
10. 4 5 6 2 1 2 9 8 2 4 3 5 1 6 2 4 5 1 6 2 9 4 3 8 7 5 1 6 2 7 4 3 5 1 6 9 8 3 1
11. 4 5 6 2 1 2 9 8 2 4 3 5 1 6 2 4 5 1 6 2 9 4 3 8 7 5 1 6 2 2 7 4 3 5 1 6 9 8 3 1
12. 4 5 6 5 6 2 1 2 9 8 2 4 3 5 1 6 2 4 5 1 6 2 9 4 3 8 7 5 1 6 2 2 7 4 3 5 1 6 9 8 3 1 4
13. 5 6 4 5 6 5 6 2 1 2 9 8 2 4 3 5 1 6 2 4 5 1 6 2 9 4 3 8 7 5 1 6 2 2 7 4 3 5 1 6 9 8 3 1 4
14. 5 6 5 4 5 6 5 6 2 1 2 9 8 2 4 3 5 1 6 2 4 5 1 6 2 9 4 3 8 7 5 1 6 2 2 7 4 3 5 1 6 9 8 3 1 4 6
15. 5 6 5 4 5 6 5 6 2 1 2 9 8 2 4 3 5 1 6 2 4 5 1 6 2 9 4 3 8 7 5 1 6 2 5 2 7 4 3 5 1 6 9 8 3 1 4 6
16. 5 6 5 4 5 6 5 6 2 1 2 9 8 9 2 4 3 5 1 6 2 4 5 1 6 2 9 4 3 8 7 5 1 6 2 5 2 7 4 3 5 1 6 9 8 3 1 4 6 8
17. 5 6 5 4 5 6 5 6 2 1 2 9 8 9 2 4 3 5 1 6 2 4 5 1 6 2 9 4 3 8 7 5 1 6 9 2 5 2 7 4 3 5 1 6 9 8 3 1 4 6 8
18. Conquer ༝ԙࢠᏐྻቮඃ pivot ෼ҝၷஈɼҰஈ খԙ౳ԙ pivot తᏐྻ Aɼ㠥Ұஈେԙ ౳ԙ pivot తᏐྻ Bɻ
19. Conquer ༝ԙࢠᏐྻቮඃ pivot ෼ҝၷஈɼҰஈ খԙ౳ԙ pivot తᏐྻ Aɼ㠥Ұஈେԙ ౳ԙ pivot తᏐྻ Bɻ A B C
20. 2 2
21. 2 2 1
22. 2 2 1
23. 1 2 1 2 2 5 2 5 1 6
24. 1 2 1 2 2 5 2 5 1 6
25. 5 6 1 2 1 2 5 6 2 5 2 5 1 6 4
26. 5 6 1 2 1 2 5 6 2 5 2 5 1 6 4
27. 4 5 6 5 6 1 2 1 2 4 5 6 5 6 2 5 2 5 1 6 4 3
28. 4 5 6 5 6 1 2 1 2 4 5 6 5 6 2 5 2 5 1 6 4 3
29. 1 2 3 4 5 6 4 5 6 5 6 1 2 1 2 4 5 6 5 6 1 2 3 4 5 6 9 2 5 2 5 9 1 6 4 3 8
30. 1 2 3 4 5 6 4 5 6 5 6 1 2 1 2 4 5 6 5 6 1 2 3 4 5 6 9 2 5 2 5 9 1 6 4 3 8
31. 8 9 1 2 3 4 5 6 8 9 4 5 6 5 6 1 2 1 2 4 5 6 5 6 1 2 3 4 5 6 9 2 5 2 5 9 7 1 6 4 3 8
32. 8 9 1 2 3 4 5 6 8 9 4 5 6 5 6 1 2 1 2 4 5 6 5 6 1 2 3 4 5 6 9 2 5 2 5 9 7 1 6 4 3 8
33. 8 9 1 2 3 4 5 6 8 9 4 5 6 5 6 1 2 1 2 4 5 6 5 6 1 2 3 4 5 6 1 2 3 4 5 6 7 8 9 9 2 5 2 5 9 7 1 6 4 3 8
34. 9 3 How to Divide 4 1 5 8 6 7 2
35. 9 3 How to Divide 4 1 5 8 6 4 7 2
36. 9 3 How to Divide 4 1 5 8 6 4 7 2
37. 9 3 How to Divide 4 1 5 8 6 4 7 2
38. 9 3 How to Divide 4 1 5 8 6 4 7 2
39. 9 3 How to Divide 4 1 5 8 6 4 7 2
40. 9 3 How to Divide 4 1 5 8 6 4 7 2
41. 9 3 How to Divide 4 1 5 8 6 4 7 2
42. 9 3 How to Divide 4 1 5 8 6 4 7 2
43. 9 3 How to Divide 4 1 5 8 6 4 7 2
44. 9 3 How to Divide 4 1 5 8 6 4 7 2 4 1 3 2 5 8 7 9 6
45. 5 6 7 8 9 3 2 1 4 How to Conquer
46. 5 6 7 8 9 3 2 1 4 How to Conquer
47. 5 6 7 8 9 3 2 1 4 How to Conquer
48. 5 6 7 8 9 3 2 1 4 How to Conquer
49. void quickSort( int L, int R ) { if ( R - L <= 1 ) return; int pivot = N[ R - 1 ], p = L; for ( int i = L; i < R - 1; ++i ) { if ( N[ i ] <= pivot ) { swap( N[ i ], N[ p ] ); ++p; } } swap( N[ R - 1 ], N[ p ] ); quickSort( L, p ); quickSort( p + 1, R ); } In-place Version
50. 9 4 3 6 5 1 8 7 How to Divide 2
51. 9 4 3 6 5 1 8 7 How to Divide 2 6
52. 9 4 3 6 5 1 8 7 How to Divide 2 2 6
53. 9 4 3 6 5 1 8 7 How to Divide 2 2 6
54. 9 4 3 6 5 1 8 7 How to Divide 2 2 2 6
55. 9 9 4 3 6 5 1 8 7 How to Divide 2 2 2 6
56. 9 9 4 4 3 6 5 1 8 7 How to Divide 2 2 2 9 6
57. 9 9 4 4 3 6 5 1 8 7 How to Divide 2 2 2 9 6
58. 9 9 4 4 3 6 5 1 8 7 How to Divide 2 2 2 9 4 6
59. 9 9 4 4 3 3 6 5 1 8 7 How to Divide 2 2 2 9 4 6
60. 9 9 4 4 3 3 6 5 1 8 7 How to Divide 2 2 2 9 4 6
61. 9 9 4 4 3 3 6 5 1 8 7 How to Divide 2 2 2 9 4 3 6
62. 9 9 4 4 3 3 6 5 1 8 7 8 How to Divide 2 2 2 9 4 3 6
63. 9 9 4 4 3 3 6 5 1 8 7 8 8 How to Divide 2 2 2 9 4 3 6
64. 9 9 4 4 3 3 6 5 1 8 7 8 7 8 How to Divide 2 2 2 9 4 3 6
65. 9 9 4 4 3 3 6 5 1 8 7 8 7 8 7 How to Divide 2 2 2 9 4 3 6
66. 9 9 4 4 3 3 6 5 1 5 8 7 8 7 8 7 How to Divide 2 2 2 9 4 3 6
67. 9 9 4 4 3 3 6 5 1 5 8 7 8 7 8 7 How to Divide 2 2 2 9 4 3 6
68. 9 9 4 4 3 3 6 5 1 5 8 7 8 7 8 7 How to Divide 2 2 2 5 9 4 3 6
69. 9 9 4 4 3 3 6 5 1 5 8 7 8 7 8 7 How to Divide 2 2 2 5 9 4 3 1 6
70. 9 9 4 4 3 3 6 5 1 5 8 7 8 7 8 7 How to Divide 2 2 2 5 9 4 3 1 6
71. 9 9 4 4 3 3 6 5 1 5 8 7 8 7 8 7 How to Divide 2 2 2 5 9 4 3 1 1 6
72. 9 9 4 4 3 3 6 5 1 5 8 7 8 7 8 7 How to Divide 2 2 2 5 9 4 3 1 1 6
73. 9 9 4 4 3 3 6 5 1 5 8 7 8 7 8 7 How to Divide 2 2 2 5 9 4 3 1 1 6 2 5 4 3 1 8 9 7
74. 6 How to Conquer 1 4 2 3 5 8 7 9 1 4 2 3 5 8 7 9
75. 6 How to Conquer 1 4 2 3 5 8 7 9 1 4 2 3 5 8 7 9
76. End