2sum.py

#!/usr/bin/env python3

import sys


def doesAny2SumTo(target, lst):
	multiset = {}
	for i in lst:
		if i in multiset:
			multiset[i] += 1
		else:
			multiset[i] = 1

	for i in lst:
		# Try to find the counterpart number where i + counterpart == target
		counterpart = target - i

		count = multiset.get(counterpart, 0)
		if ((counterpart == i and count >= 2) or
				(counterpart != i and count >= 1)):
			return True

	return False


if __name__ == "__main__":
	if len(sys.argv) < 3:
		print(f"{sys.argv[0]} TARGET NUM [NUM ...]", file=sys.stderr)

	print(doesAny2SumTo(int(sys.argv[1]), [int(i) for i in sys.argv[2:]]))