day 17 puzzle 1

progress.yaml

@@ -28,3 +28,7 @@
   stars: 2
 15:
   stars: 2
+16:
+  stars: 0
+17:
+  stars: 1

res/examples/day17.txt

@@ -0,0 +1,5 @@
+Register A: 729
+Register B: 0
+Register C: 0
+
+Program: 0,1,5,4,3,0

src/day17/puzzle1.typ

@@ -0,0 +1,85 @@
+#import "/src/utils.typ": *
+
+#let ADV = 0
+#let BXL = 1
+#let BST = 2
+#let JNZ = 3
+#let BXC = 4
+#let OUT = 5
+#let BDV = 6
+#let CDV = 7
+
+#let get-combo(regs, value) = {
+  if value >= 7 {
+    panic()
+  }
+  if value <= 3 {
+    return value
+  }
+  return regs.at(value - 4)
+}
+
+#let solve(input) = {
+  let (registers, program) = input.split("\n\n")
+
+  let regs = ()
+  for line in registers.split("\n") {
+    regs.push(
+      int(
+        line.split(": ")
+            .last()
+      )
+    )
+  }
+  program = program.split(": ")
+                   .last()
+                   .split(",")
+                   .map(int)
+
+  let out = ()
+  let pc = 0
+  while pc < program.len() {
+    let op = program.at(pc)
+    let val = program.at(pc + 1)
+    if op == ADV {
+      let num = regs.at(0)
+      let den = get-combo(regs, val)
+      let res = num.bit-rshift(den)
+      regs.at(0) = res
+    } else if op == BXL {
+      regs.at(1) = regs.at(1).bit-xor(val)
+    } else if op == BST {
+      regs.at(1) = get-combo(regs, val).bit-and(0b111)
+    } else if op == JNZ {
+      if regs.at(0) != 0 {
+        pc = val
+        continue
+      }
+    } else if op == BXC {
+      regs.at(1) = regs.at(1).bit-xor(regs.at(2))
+    } else if op == OUT {
+      out.push(get-combo(regs, val).bit-and(0b111))
+    } else if op == BDV {
+      let num = regs.at(0)
+      let den = get-combo(regs, val)
+      let res = num.bit-rshift(den)
+      regs.at(1) = res
+    } else if op == CDV {
+      let num = regs.at(0)
+      let den = get-combo(regs, val)
+      let res = num.bit-rshift(den)
+      regs.at(2) = res
+    } else {
+      panic("Unknown instruction " + str(op))
+    }
+    pc += 2
+  }
+
+  return out.map(str).join(",")
+}
+
+#show-puzzle(
+  17, 1,
+  solve,
+  example: "4,6,3,5,6,3,5,2,1,0"
+)