Sorting & Searching alGOrithms

A presentation explaining Quicksort and Binary Search in Go with Testing and Benchmarks.

Transcript

1. Sorting & Searching alGOrithms Kaylyn Gibilterra Gotham Go 2018 Capital One Labs @kgibilterra
2. algorithms are terrible
3. alGOrithms are great
4. 1. Sorting Algorithms - Quicksort 2. Searching Algorithms - Binary Search
5. 1. New to Go Who is this talk for?
6. 1. New to Go 2. New to algorithms Who is this talk for?
7. 1. New to Go 2. New to algorithms 3. I already know these, why am I here Who is this talk for?
8. Sorting Algorithms
9. Sorting Algorithms
10. Quicksort “Given an array, one element is chosen and the others are partitioned into two subsets-those less than the partition element and those greater than or equal to it. The same process is then applied recursively to the two subsets. When a subset has fewer than two elements, it doesn't need any sorting; this stops the recursion.” Kernighan and Ritchie
11. E A D C B F G E R T U D E O B L I C E U G E N E R E D A R O L A V I D
12. E A D C B F G
13. E A D C B F G pivot
14. D C E G B F A
15. E A D C B F G pivot
16. E A D C B F G pivot B < D
17. E A D C B F G pivot split B < D
18. E A D C B F G pivot split B < D
19. E A D C B F G pivot split G > D
20. E A D C B F G pivot split A < D
21. E A D C B F G pivot split swap A < D
22. E G D C B F A pivot swap split A < D
23. E G D C B F A pivot split A < D
24. E G D C B F A pivot split E > D
25. E G D C B F A pivot split F > D
26. E G D C B F A pivot split C < D
27. E G D C B F A pivot split swap C < D
28. E C D G B F A pivot swap split C < D
29. E C D G B F A pivot split C < D
30. E C D G B F A pivot split
31. E C D G B F A pivot split swap
32. D C E G B F A split swap
33. D C E G B F A split final
34. D C E G B F A left array right array
35. C B A pivot
36. C B A pivot split
37. C B A pivot split
38. C B A pivot split
39. C B A pivot split
40. C B A pivot split
41. C B A final split
42. C B A left array
43. B A
44. B A pivot
45. B A pivot split
46. B A pivot split
47. B A pivot split swap
48. A B split swap
49. A B split final
50. A B right array
51. A B final
52. D C E G A F B left array right array
53. E G F pivot
54. E G F pivot split
55. E G F pivot split
56. E G F pivot split
57. E G F pivot split swap
58. F G E split swap
59. F G E final right array
60. F G pivot
61. F G pivot split
62. F G pivot split
63. F G pivot split swap
64. G F split swap
65. G F final right array
66. G F final
67. D C G F A E B
68. Quicksort alGOrithm
69. Quicksort alGOrithm
70. Quicksort Test
71. Quicksort Test
72. Quicksort Test
73. Quicksort Benchmark
74. Quicksort Benchmark go test -bench=.
75. Quicksort Benchmark
76. Quicksort Benchmark
77. Quicksort Benchmark
78. Binary Search Search a sorted array by repeatedly dividing the search interval in half. Begin with an interval covering the whole array. If the value of the search key is less than the item in the middle of the interval, narrow the interval to the lower half. Otherwise narrow it to the upper half. Repeatedly check until the value is found or the interval is empty. GeeksForGeeks
79. D C G F A E B
80. D C G F A E B
81. D C G F A E B
82. D C G F A E B lo hi
83. D C G F A E B lo hi mid
84. D C G F A E B lo hi mid E > D
85. D C G F A E B lo hi mid E > D left array right array
86. D G F E hi mid E > D right array lo
87. G F E hi lo
88. G F E hi E < F lo mid
89. G F E hi E < F lo mid right array left array
90. F E E < F lo mid left array hi
91. E E = E lo hi
92. E E = E lo hi mid
93. E E = E
94. What would happen if we were looking for an element in-between E and F?
95. E hi lo F
96. E hi lo D
97. Binary Search alGOrithm
98. Binary Search Test
99. Binary Search Benchmark
100. Binary Search Stress Test
101. Binary Search Stress Test
102. Binary Search Stress Test
103. Binary Search Stress Test
104. Binary Search Stress Test
105. Binary Search Stress Test
106. alGOrithms are great
107. Contact me Kaylyn Gibilterra @kgibilterra kaylyn.gibilterra@capitalone.com