# merge.py

Below is the syntax highlighted version of merge.py from §4.2 Sorting and Searching.

```#-----------------------------------------------------------------------
# merge.py
#-----------------------------------------------------------------------

import sys
import stdio
import stdarray

#-----------------------------------------------------------------------

# Merge a[lo:mid] with a[mid:hi] using aux as auxiliary memory.

def _merge(a, lo, mid, hi, aux):
n = hi - lo
i = lo
j = mid
for k in range(n):
if i == mid:
aux[k] = a[j]
j += 1
elif j == hi:
aux[k] = a[i]
i += 1
elif a[j] < a[i]:
aux[k] = a[j]
j += 1
else:
aux[k] = a[i]
i += 1
a[lo:hi] = aux[0:n]

#-----------------------------------------------------------------------

# Sort a[lo:hi] into increasing order, using array aux as auxiliary
# memory.

def _sort(a, lo, hi, aux):
n = hi - lo
if n <= 1:
return
mid = (lo + hi) // 2
_sort(a, lo, mid, aux)
_sort(a, mid, hi, aux)
_merge(a, lo, mid, hi, aux)

#-----------------------------------------------------------------------

# Sort array a into increasing order.

def sort(a):
n = len(a)
aux = stdarray.create1D(n)
_sort(a, 0, n, aux)

#-----------------------------------------------------------------------

# Read strings from standard input, sort them into
# increasing order, and write them to standard output.

def main():
sort(a)
for s in a:
stdio.write(s + ' ')
stdio.writeln()

if __name__ == '__main__':
main()

#-----------------------------------------------------------------------

# more tiny.txt
# the and was his you tom but for had him

# python merge.py < tiny.txt
# and but for had him his the tom was you

# python insertion.py < tomsawyer.txt
# ... (Works quickly.)

```