def xmerge(*ln):
""" Iterator version of merge.
Assuming l1, l2, l3...ln sorted sequences, return an iterator that
yield all the items of l1, l2, l3...ln in ascending order.
Input values doesn't need to be lists: any iterable sequence can be used.
"""
pqueue = []
for i in map(iter, ln):
try:
pqueue.append((i.next(), i.next))
except StopIteration:
pass
pqueue.sort()
pqueue.reverse()
X = max(0, len(pqueue) - 1)
while X:
d,f = pqueue.pop()
yield d
try:
# Insort in reverse order to avoid pop(0)
lo, hi, d = 0, X, f()
while lo < hi:
mid = (lo+hi)//2
if d > pqueue[mid][0]: hi = mid
else: lo = mid+1
pqueue.insert(lo, (d,f))
except StopIteration:
X-=1
if pqueue:
d,f = pqueue[0]
yield d
try:
while 1: yield f()
except StopIteration:pass
def merge(*ln):
""" Merge several sorted sequences into a sorted list.
Assuming l1, l2, l3...ln sorted sequences, return a list that contain
all the items of l1, l2, l3...ln in ascending order.
Input values doesn't need to be lists: any iterable sequence can be used.
"""
return list(xmerge(*ln))
