accept input file as cmdline argument

2019/day1/day1.py

@@ -32,10 +32,13 @@ def test_part2():
 
 
 if __name__ == "__main__":
-    print("Part 1 - total mass: ", calculate_total_fuel_mass("./input.txt"))
+    import sys
+    infile = sys.argv[1] if len(sys.argv) > 1 else "example.txt"
+
+    print("Part 1 - total mass: ", calculate_total_fuel_mass(infile))
 
     test_part2()
     print(
         "Part 2 -- total mass: ",
-        calculate_total_fuel_mass("./input.txt", calculate_fuel_iterative),
+        calculate_total_fuel_mass(infile, calculate_fuel_iterative),
     )

2019/day2/day2.py

@@ -54,7 +54,9 @@ def run_program(memory, noun, verb):
 
 if __name__ == "__main__":
     tests()
-    with open("input.txt") as inp:
+    import sys
+    infile = sys.argv[1] if len(sys.argv) > 1 else "example.txt"
+    with open(infile) as inp:
         memory = [int(x) for x in inp.readline().strip().split(",")]
         # Pass a copy to avoid modifying the original memory
         print("Part 1 answer: ", run_program(memory[:], 12, 2))

2019/day3/day3.py

@@ -70,8 +70,9 @@ def tests():
 
 if __name__ == "__main__":
     tests()
-
-    with open("input.txt") as raw_input:
+    import sys
+    infile = sys.argv[1] if len(sys.argv) > 1 else "example.txt"
+    with open(infile) as raw_input:
         lines = raw_input.readlines()
         wire1, wire2 = [line.strip("\n").split(",") for line in lines]
         print("Part 1 -- distance = ", find_min_distance(wire1, wire2))