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@EdisonChendi
Created April 14, 2018 13:06
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merge sort + merge n sorted list with variable length
#coding:UTF-8
import math
def merge_sort(l):
if len(l) <= 1:
return l
mid_idx = (len(l)-0)//2
left = l[0:mid_idx]
right = l[mid_idx:]
sorted_left = merge_sort(left)
sorted_right = merge_sort(right)
return merge(sorted_left, sorted_right)
# def merge(left, right):
# i = j = 0
# len_left = len(left)
# len_right = len(right)
# merged = []
# while i < len_left and j < len_right:
# l = left[i]
# r = right[j]
# if l < r:
# merged.append(l)
# i += 1
# else:
# merged.append(r)
# j += 1
# if i == len_left:
# merged.extend(right[j:])
# if j == len_right:
# merged.extend(left[i:])
# return merged
# def merge(left, right):
# iter_left = iter(left)
# iter_right = iter(right)
# l = next(iter_left)
# r = next(iter_right)
# merged = []
# while True:
# if l < r:
# merged.append(l)
# try:
# l = next(iter_left)
# except StopIteration:
# merged.append(r)
# merged.extend(iter_right)
# return merged
# else:
# merged.append(r)
# try:
# r = next(iter_right)
# except StopIteration:
# merged.append(l)
# merged.extend(iter_left)
# return merged
def merge(*n_sorted_lists):
# assume every list has length > 0
n_sorted_lists = [iter(l) for l in n_sorted_lists]
cp = [next(i) for i in n_sorted_lists]
merged = []
while True:
min_ele_idx, min_ele = get_min(cp)
merged.append(min_ele)
min_ele_list = n_sorted_lists[min_ele_idx]
try:
m = next(min_ele_list)
cp[min_ele_idx] = m
except StopIteration:
n_sorted_lists.remove(min_ele_list)
del cp[min_ele_idx]
if len(cp) == 0:
break
return merged
def get_min(l):
m_idx, m = -1, math.inf
for i, v in enumerate(l):
if v < m:
m_idx = i
m = v
else:
pass
return m_idx, m
l = [7, 3, 8, 10, 11, 1, 6]
print(l)
s = merge_sort(l)
print(s)
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