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  • 常见排序算法-Python实现

    常见排序算法-Python实现

    python
    排序
    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递增排序 way=0递减排序 
    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. # 加入排序判断标志，可提高运行效率 
    28. # way=1递增排序 way=0递减排序 
    29. def better_bubble_sort(array,way=1): 
    30. is_sorted = True # 判断记录上次遍历是否进行过交换，若没有则表示不用再遍历了 
    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.归并排序

        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.选择排序

        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. # 递归 
    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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  • 原文地址：https://www.cnblogs.com/marsggbo/p/6622888.html
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