import numpy as np
# 执行过程
"""
nums = [17, 15, 9, 4, 8, 2, 15, 0, 11, 4]
Front: [17]
Behind: [15]
Ret: [15, 17]
Front: [15, 17]
Behind: [9]
Ret: [9, 15, 17]
Front: [4]
Behind: [8]
Ret: [4, 8]
Front: [9, 15, 17]
Behind: [4, 8]
Ret: [4, 8, 9, 15, 17]
Front: [2]
Behind: [15]
Ret: [2, 15]
Front: [2, 15]
Behind: [0]
Ret: [0, 2, 15]
Front: [11]
Behind: [4]
Ret: [4, 11]
Front: [0, 2, 15]
Behind: [4, 11]
Ret: [0, 2, 4, 11, 15]
Front: [4, 8, 9, 15, 17]
Behind: [0, 2, 4, 11, 15]
Ret: [0, 2, 4, 4, 8, 9, 11, 15, 15, 17]
[0, 2, 4, 4, 8, 9, 11, 15, 15, 17]
"""
class Merge():
def merge_sort(self, nums):
if nums is None or len(nums) == 0 or len(nums) == 1:
return nums
return self.merge_sort_worker(nums, 0, len(nums) - 1)
def merge_sort_worker(self, nums, left, right):
if left >= right:
return nums
# split
mid = (left + right) >> 1
x = nums[:mid+1]
y = nums[mid+1:]
front = self.merge_sort_worker(x, 0, len(x) - 1)
behind = self.merge_sort_worker(y, 0, len(y) - 1)
# merge
print("Front: ", front)
print("Behind: ", behind)
ret = self.merge_worker(front, behind)
print("Ret: {} \n".format(ret))
return ret
def merge_worker(self, front, behind):
new_nums = [None for i in range(len(front) + len(behind))]
i, j = 0, 0
idx = 0
while i < len(front) and j < len(behind):
if front[i] < behind[j]:
new_nums[idx] = front[i]
i += 1
else:
new_nums[idx] = behind[j]
j += 1
idx += 1
while i < len(front):
new_nums[idx] = front[i]
idx += 1
i += 1
while j < len(behind):
new_nums[idx] = behind[j]
idx += 1
j += 1
return new_nums
if __name__ == '__main__':
nums = [17, 15, 9, 4, 8, 2, 15, 0, 11, 4]
sol = Merge()
ret = sol.merge_sort(nums)
print(ret)
