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def merge_sort(a):
def merge_array(a, i, j):
if i >= j:
return a
def merge(a, left_i, left_j, right_i, right_j):
new_a = []
i, j = left_i, right_i
while i <= left_j and j <= right_j:
if a[i] <= a[j]:
pos = i
i += 1
else:
pos = j
j += 1
new_a.append(a[pos])
if i <= left_j:
new_a.extend(a[i:left_j+1])
if right_i <= right_j:
new_a.extend(a[j:right_j+1])
a[left_i:right_j+1] = new_a
mid = i + (j - i) // 2
merge_array(a, i, mid)
merge_array(a, mid+1, j)
merge(a, i, mid, mid+1, j)
return a
return merge_array(a, 0, len(a)-1)
if __name__ == "__main__":
print(merge_sort([1, 3, 2, 4, 6, 8, 7]))
print(merge_sort([8]))
print(merge_sort([9, 8, 7, 4, 3, 2, 0]))
print(merge_sort([9, 10, 12, 14, 13, 22, 100]))
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