From d13666f520159067a4badb4521502fa24a14a957 Mon Sep 17 00:00:00 2001
From: Luke Hubmayer-Werner <mongoose41@gmail.com>
Date: Fri, 21 Dec 2018 17:09:29 +1030
Subject: [PATCH] Added specialised 2018 Day 21 solution

---
 2018/day21-input |  32 +++++++++++++
 2018/day21.py    | 115 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 147 insertions(+)
 create mode 100644 2018/day21-input
 create mode 100644 2018/day21.py

diff --git a/2018/day21-input b/2018/day21-input
new file mode 100644
index 0000000..621f0ba
--- /dev/null
+++ b/2018/day21-input
@@ -0,0 +1,32 @@
+#ip 2
+seti 123 0 5
+bani 5 456 5
+eqri 5 72 5
+addr 5 2 2
+seti 0 0 2
+seti 0 9 5
+bori 5 65536 3
+seti 7586220 4 5
+bani 3 255 1
+addr 5 1 5
+bani 5 16777215 5
+muli 5 65899 5
+bani 5 16777215 5
+gtir 256 3 1
+addr 1 2 2
+addi 2 1 2
+seti 27 9 2
+seti 0 9 1
+addi 1 1 4
+muli 4 256 4
+gtrr 4 3 4
+addr 4 2 2
+addi 2 1 2
+seti 25 4 2
+addi 1 1 1
+seti 17 2 2
+setr 1 6 3
+seti 7 8 2
+eqrr 5 0 1
+addr 1 2 2
+seti 5 0 2
diff --git a/2018/day21.py b/2018/day21.py
new file mode 100644
index 0000000..43d4a68
--- /dev/null
+++ b/2018/day21.py
@@ -0,0 +1,115 @@
+with open('day21-input', 'r') as file:
+  data = [l.strip('\n') for l in file]
+
+# This solution includes optimisations which only work for this input.
+# To adapt it to other inputs, the exit condition must be identified and the other optimisations removed.
+
+class oper_factory:
+  def __init__(self, operator, immediate_a, immediate_b):
+    self.operator = operator
+    self.immediate_a = immediate_a
+    self.immediate_b = immediate_b
+
+  def __call__(self, regs, opcodes):
+    op, a, b, c = opcodes
+    r = list(regs)
+    r[c] = self.operator((a if self.immediate_a else regs[a]), (b if self.immediate_b else regs[b]))
+    return r
+
+bin_ops = (int.__add__, int.__mul__, int.__and__, int.__or__)
+set_op = lambda a, b: a  # Just discard second operand
+comp_ops = (int.__gt__, int.__eq__)
+comp_imms = ((True, False), (False, True), (False, False))  # ir, ri, rr
+
+instructions = [oper_factory(op, False, imm) for op in bin_ops for imm in (False, True)] \
+             + [oper_factory(set_op, imm, True) for imm in (False, True)] \
+             + [oper_factory(op, *imm) for op in comp_ops for imm in comp_imms]
+inst_names = ('addr', 'addi', 'mulr', 'muli', 'banr', 'bani', 'borr', 'bori', 'setr', 'seti', 'gtir', 'gtri', 'gtrr', 'eqir', 'eqri', 'eqrr')
+insts = {name: func for name, func in zip(inst_names, instructions)}
+
+ops = {}
+ops['seti'] = 0
+
+registers = [0,0,0,0,0,0]
+ip_r = int(data[0].split()[-1])
+tokens_ = []
+for line in data[1:]:
+  tokens = line.split()
+  tokens_.append([insts[tokens[0]]] + [int(i) for i in tokens[1:]])
+
+
+def run_program(initial_registers):
+  registers = initial_registers.copy()
+  past_comps = set()
+  past_comps_l = []
+  for j in range(100000000000):
+    # print(registers)
+    try:
+      i = registers[ip_r]
+      if i == 17:
+        registers[1] = (registers[3]//256)-1
+        registers[ip_r] += 1
+        continue
+      if i == 9:
+        registers[5] = (((registers[5]+registers[1])&0xFFFFFF) * 65899) & 0xFFFFFF
+        registers[ip_r] = 13
+        continue
+      if i == 28:
+        # print(registers)
+        if registers[5] in past_comps:
+          # print('Loop???')
+          return past_comps_l
+        past_comps.add(registers[5])
+        past_comps_l.append(registers[5])
+      opcodes = tokens_[i]
+      registers = opcodes[0](registers, opcodes)
+    except Exception:
+      print(f'Halted at cycle {j}!')
+      return j
+    registers[ip_r] += 1
+  print(f'Did not halt! {registers}')
+  return 1000000
+
+past_comps_l = run_program([0,0,0,0,0,0])
+print(past_comps_l[0])  # Part 1
+print(past_comps_l[-1])  # Part 2
+
+# #ip 2
+# L00 - seti 123 0 5
+# L01 - bani 5 456 5
+# L02 - eqri 5 72 5    - r5 = (r5 == 72)
+# L03 - addr 5 2 2     - r2 += r5
+# L04 - seti 0 0 2     - r2 = 0 (goto L01)
+# L05 - seti 0 9 5     - r5 = 0
+# L06 - bori 5 65536 3     - r3 = r5 | 0x010000  <-- Insertion point after comparison
+# L07 - seti 7586220 4 5   - r5 = 7586220
+# [FUNCTION]
+# L08 - bani 3 255 1       - r1 = r3 & 0xFF  <-- insertion point
+# L09 - addr 5 1 5         - r5 += r1
+# L10 - bani 5 16777215 5  - r5 &= 0x00FFFFFF
+# L11 - muli 5 65899 5     - r5 *= 65899
+# L12 - bani 5 16777215 5  - r5 &= 0x00FFFFFF
+# L13 - gtir 256 3 1       - r1 = 256 > r3  (not if executed sequentially)
+# L14 - addr 1 2 2         - r2 += r1 (goto L16->L28 if 256>r3)  !!!
+# L15 - addi 2 1 2         - r2 += 1 (goto L17)
+# L16 - seti 27 9 2   - r2 = 27 (goto L28 - comparison)
+
+# L17 - seti 0 9 1         - r1 = 0
+# [FUNCTION]
+# L18 - addi 1 1 4         - r4 = r1 + 1  <-- insertion point
+# L19 - muli 4 256 4       - r4 *= 256
+# L20 - gtrr 4 3 4         - r4 = r4 > r3
+# L21 - addr 4 2 2   - r2 += r4 (goto L23->L26 if (r1+1)*256 > r3. r3=r1 then goto L08)
+# L22 - addi 2 1 2   - r2 += 1 (goto L24 increment r1 and goto L18)
+# [FUNCTION]
+# L28 - eqrr 5 0 1   - r1 = r5==r0    - Exit condition!  - 11050031 is lowest
+# L29 - addr 1 2 2   - r2 += r1
+# L30 - seti 5 0 2   - r2 = 5         - Goto L06
+
+
+
+# L23 - seti 25 4 2  - r2 = 25 (goto L26)
+# L24 - addi 1 1 1   - r1 += 1
+# L25 - seti 17 2 2  - r2 = 17 (goto L18)
+# L26 - setr 1 6 3   - r3 = r1
+# L27 - seti 7 8 2   - r2 = 7 (goto L08)
\ No newline at end of file