常見排序演算法-Python實現

marsggbo發表於2017-03-26
排序演算法Python

常見排序演算法-Python實現

python
排序
演算法

1.二分法

    python    32行
  1. #coding=utf-8 
  2. def binary_search(input_array, value): 
  3. “””Your code goes here.””” 
  4. length = len(input_array) 
  5. left = 0 
  6. right = length-1 
  7. if length == 1: 
  8. return 0 if value == input_value[0] else –1 
  9. else: 
  10. mid = (left+right)/2 
  11. while(right-left>1): 
  12. if input_array[mid] == value: 
  13. return mid 
  14. elif input_array[mid] > value: 
  15. right = mid 
  16. mid = (left+right)/2 
  17. else: 
  18. left = mid 
  19. mid = (left+right)/2 
  20. if input_array[left] == value: 
  21. return left 
  22. elif input_array[right] == value: 
  23. return right 
  24. else: 
  25. return –1 
  26.  
  27. test_list = [1,3,9,11,15,19,29] 
  28. test_val1 = 25 
  29. test_val2 = 15 
  30. print (binary_search(test_list, test_val1)) 
  31. print (binary_search(test_list, test_val2)) 

2.冒泡法

    python    60行
  1. #coding=utf-8 
  2.  
  3. # way=1遞增排序 way=0遞減排序 
  4. def bubble_sort(array,way=1): 
  5. length = len(array) 
  6.  
  7. if not length: 
  8. print(“Error!The length of array must be greater than 0.
    “    ) 
  9. return `Wrong array`  
  10.  
  11. if way == 1: 
  12. while length > 0: 
  13. for i in range(length-1): 
  14. if array[i] > array[i+1]: 
  15. array[i],array[i+1] = array[i+1],array[i] 
  16. length -= 1 
  17. return array 
  18.  
  19. elif way == 0: 
  20. while length > 0: 
  21. for i in range(length-1): 
  22. if array[i] < array[i+1]: 
  23. array[i],array[i+1] = array[i+1],array[i] 
  24. length -= 1 
  25. return array 
  26.  
  27. # 加入排序判斷標誌，可提高執行效率 
  28. # way=1遞增排序 way=0遞減排序 
  29. def better_bubble_sort(array,way=1): 
  30. is_sorted = True # 判斷記錄上次遍歷是否進行過交換，若沒有則表示不用再遍歷了 
  31. length = len(array) 
  32.  
  33. if not length: 
  34. print(“Error!The length of array must be greater than 0.
    “    ) 
  35. return `Wrong array`  
  36.  
  37. if way == 1: 
  38. while length > 0 and is_sorted: 
  39. for i in range(length-1): 
  40. is_sorted = False 
  41. if array[i] > array[i+1]: 
  42. array[i],array[i+1] = array[i+1],array[i] 
  43. is_sorted = True 
  44. length -= 1 
  45. return array 
  46.  
  47. elif way == 0: 
  48. while length > 0 and is_sorted: 
  49. for i in range(length-1): 
  50. is_sorted = False 
  51. if array[i] < array[i+1]: 
  52. array[i],array[i+1] = array[i+1],array[i] 
  53. is_sorted = True 
  54. length -= 1 
  55. return array 
  56.  
  57.  
  58. test = [21, 4, 1, 3, 9, 20, 25, 6, 21, 14]  
  59. print(better_bubble_sort(test,1)) 

3.插入排序

    python    19行
  1. #coding=utf-8 
  2.  
  3. def insert_sort(array): 
  4. length = len(array) 
  5. flag = array[0] 
  6. for x in range(1,length): 
  7. # 之前的 
  8. if array[x] < array[x-1]: 
  9. flag = array[x] 
  10. y = x 
  11. while y != 0 and array[y-1] > flag : 
  12. array[y] = array[y-1] 
  13. y -= 1 
  14. array[y] = flag 
  15. return array 
  16.  
  17. test = [21, 4, 1, 3, 9, 20, 25, 20, 3] 
  18. print(insert_sort(test)) 

4.歸併排序

    python    31行
  1. #coding=utf-8 
  2.  
  3. def merge_sort(array): 
  4. if len(array) <= 1: 
  5. return array 
  6.  
  7. split_index = len(array)/2 
  8. left = merge_sort(array[:split_index]) 
  9. right = merge_sort(array[split_index:]) 
  10. return merge(left,right) 
  11.  
  12. def merge(left,right): 
  13. i = 0 
  14. j = 0 
  15. result = [] 
  16. while i < len(left) and j < len(right): 
  17. if left[i] <= right[j]: 
  18. result.append(left[i]) 
  19. i += 1 
  20. else: 
  21. result.append(right[j]) 
  22. j += 1 
  23.  
  24. result += (left[i:]) 
  25. result += (right[j:]) 
  26. return result 
  27.  
  28. a = [1,2] 
  29. test = [21, 4, 1, 3, 9, 20, 25]  
  30. print(merge_sort(test)) 

5.選擇排序

    python    16行
  1. #coding=utf-8 
  2.  
  3. def select_sort(array): 
  4. length = len(array) 
  5. # mini = array[0] 
  6. for i in range(length): 
  7. mini = array[i] 
  8. for j in range(i,length): 
  9. if array[j] < mini: 
  10. mini = array[j] 
  11. array[i],array[j] = array[j],array[i] 
  12. return array 
  13.  
  14. test = [21, 4, 1, 3, 9, 20, 25, 20, 3]  
  15. print(select_sort(test)) 

6.快速排序

    python    26行
  1. #coding=utf-8 
  2.  
  3. # 遞迴 
  4. def quick_sort(lists, left, right): 
  5. # 快速排序 
  6. if left >= right: 
  7. return lists 
  8. key = lists[left] 
  9. low = left 
  10. high = right 
  11. while left < right: 
  12. while left < right and lists[right] >= key: 
  13. right -= 1 
  14. lists[left] = lists[right] 
  15. while left < right and lists[left] <= key: 
  16. left += 1 
  17. lists[right] = lists[left] 
  18. lists[right] = key 
  19. quick_sort(lists, low, left – 1) 
  20. quick_sort(lists, left + 1, high) 
  21. return lists 
  22.  
  23.  
  24. test = [21, 4, 1, 3, 9, 20, 25, 6, 21, 14] 
  25. print (quick_sort(test,0,len(test)-1)) 

written by MARSGGBO 
2017-2-14


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