diff --git a/adventofcode/2015/day7/day7.py b/adventofcode/2015/day7/day7.py
new file mode 100644
index 0000000..0008ea0
--- /dev/null
+++ b/adventofcode/2015/day7/day7.py
@@ -0,0 +1,77 @@
+#!/usr/bin/env python3
+import fileinput
+
+
+def parse_circuit(inp):
+    instructions = {}
+    # dst: (OP, ARGS)
+    for line in inp:
+        op, dst = line.split(" -> ")
+        op = op.split(" ")
+        if len(op) == 1:  # ASSIGN
+            src = op[0]
+            instructions[dst] = ("ASSIGN", src)
+        elif len(op) == 2:  # NOT
+            assert op[0] == "NOT"
+            instructions[dst] = ("NOT", op[1])
+        elif len(op) == 3:  # BINARY OP
+            instructions[dst] = (op[1], (op[0], op[2]))
+    return instructions
+
+
+def main(inp):
+    instructions = parse_circuit(inp)
+    res = evaluate_instruction("a", instructions)
+    print("Part 1: ", res)
+    instructions["b"] = ("ASSIGN", str(res))
+    res = evaluate_instruction("a", instructions, state={})  # reset state
+    print("Part 2: ", res)
+
+
+def evaluate_instruction(start_wire, instructions, state={}):
+    if start_wire in state:
+        return state[start_wire]
+
+    op, args = instructions[start_wire]
+    result = -1
+    if op == "ASSIGN":
+        if args.isdigit():
+            result = int(args)
+        else:
+            result = evaluate_instruction(args, instructions, state)
+    elif op == "NOT":
+        if args.isdigit():
+            result = 65535 - int(args)
+        else:
+            result = 65535 - evaluate_instruction(args, instructions, state)
+    elif op in ["AND", "OR", "LSHIFT", "RSHIFT"]:
+        left, right = args
+        if left.isdigit():
+            left = int(left)
+        else:
+            left = evaluate_instruction(left, instructions, state)
+        if right.isdigit():
+            right = int(right)
+        else:
+            right = evaluate_instruction(right, instructions, state)
+        match op:
+            case "OR":
+                result = left | right
+            case "AND":
+                result = left & right
+            case "LSHIFT":
+                result = left << right
+            case "RSHIFT":
+                result = left >> right
+            case _:
+                assert False, "Unreachable"
+    else:
+        assert False, "Unreachable"
+
+    state[start_wire] = result
+    return result
+
+
+if __name__ == "__main__":
+    lines = [x.rstrip() for x in fileinput.input()]
+    main(lines)