import 2020 aoc

2020/day8/day8.py

@@ -0,0 +1,49 @@
+#! /usr/bin/env python3
+
+
+def part1(instructions):
+    instruction_pointer = 0
+    accumulator = 0
+    visited_instructions = set()
+    while instruction_pointer not in visited_instructions:  # return before executing any instruction a second time
+        if instruction_pointer >= len(instructions):  # stop the program when ip is out of bounds
+            break
+        visited_instructions.add(instruction_pointer)
+        instruction, argument = instructions[instruction_pointer].split(" ")
+        if instruction == "acc":
+            accumulator += int(argument)
+            instruction_pointer += 1
+        elif instruction == "jmp":
+            value = int(argument)
+            instruction_pointer += value
+        else:
+            instruction_pointer += 1
+    return instruction_pointer, accumulator
+
+
+def part2(instructions):
+    for index, line in enumerate(instructions):
+        permutation = generate_permutation(instructions, line, index)
+        if permutation is None:
+            continue
+        instruction_pointer, accumulator = part1(permutation)
+        if instruction_pointer == len(permutation):
+            return accumulator
+
+
+def generate_permutation(instructions, line, index):
+    permutation = instructions[:]
+    instruction, arg = line.split(" ")
+    if instruction == "acc":  # don't replace acc operations
+        return
+    elif instruction == "nop":
+        permutation[index] = f"jmp {arg}"
+    elif instruction == "jmp":
+        permutation[index] = f"nop {arg}"
+    return permutation
+
+
+if __name__ == "__main__":
+    instructions = [line.rstrip() for line in open("input.txt")]
+    print("Part 1 : (ip, acc) ", part1(instructions)[1])
+    print("Part 2 : (ip, acc) ", part2(instructions))