d17

day17/d17p1.swift

@@ -0,0 +1,45 @@
+import Foundation
+
+/*
+0 adv: A / 2^OP -> A
+1 bxl: B xor LIT -> B
+2 bst: OP % 8 -> B
+3 jnz: jump LIT if A != 0
+4 bxc: B xor C -> B (ignore op/lit)
+5 out: OP % 8 -> screen
+6 bdv: A / 2^OP -> B
+7 cdv: A / 2^OP -> C
+
+adv 1 // A = A / 2
+out A // print(A % 8)
+jnz 0 // loop while A != 0
+
+
+2,4, 1,1, 7,5, 1,5, 4,0, 5,5, 0,3, 3,0
+bst 4 // B = A % 8
+bxl 1 // B = B xor 1
+cdv 5 // C = A / 2^B
+bxl 5 // B = B xor 5
+bxc 0 // B = B xor C
+out 5 // print(B % 8)
+adv 3 // A = A / 2^3
+jnz 0 // loop while A != 0
+*/
+
+// let prog = [2,4, 1,1, 7,5, 1,5, 4,0, 5,5, 0,3, 3,0]
+//var A = 164279024971709
+var A = 164279024971453
+var B = 0
+var C = 0
+
+while true {
+    B = A % 8  // 1
+    B = B ^ 1  // 2
+    C = A >> B // 3
+    B = B ^ 5  // 4
+    B = B ^ C  // 5
+    print(B % 8, terminator: ",")
+    A = A >> 3
+    if A == 0 { break }
+}
+

day17/d17p2.swift

@@ -0,0 +1,100 @@
+import Foundation
+
+/*
+0 adv: A / 2^OP -> A
+1 bxl: B xor LIT -> B
+2 bst: OP % 8 -> B
+3 jnz: jump LIT if A != 0
+4 bxc: B xor C -> B (ignore op/lit)
+5 out: OP % 8 -> screen
+6 bdv: A / 2^OP -> B
+7 cdv: A / 2^OP -> C
+
+adv 1 // A = A / 2
+out A // print(A % 8)
+jnz 0 // loop while A != 0
+
+
+2,4, 1,1, 7,5, 1,5, 4,0, 5,5, 0,3, 3,0
+bst 4 // B = A % 8
+bxl 1 // B = B xor 1
+cdv 5 // C = A / 2^B
+bxl 5 // B = B xor 5
+bxc 0 // B = B xor C
+out 5 // print(B % 8)
+adv 3 // A = A / 2^3
+jnz 0 // loop while A != 0
+*/
+
+extension RangeReplaceableCollection where Self: StringProtocol {
+    func paddingToLeft(upTo length: Int, using element: Element = " ") -> SubSequence {
+        return repeatElement(element, count: Swift.max(0, length-count)) + suffix(Swift.max(count, count-length))
+    }
+}
+
+let prog = [2,4, 1,1, 7,5, 1,5, 4,0, 5,5, 0,3, 3,0]
+
+var A0 = -1
+var Asuffixlen = 16
+var Asuffixes = [0b0110111010111101, 0b0110111110111101]
+var maxLen = 0
+aLoop: while true {
+    A0 += 1
+    for suffix in Asuffixes {
+        //var A = A0 // do this at the beginning to find the suffixes
+        let Ax = (A0 << Asuffixlen) | suffix
+        var A = Ax
+        var B = 0
+        var C = 0
+        progLoop: for i in 0..<prog.count {
+            B = A % 8  // 1
+            B = B ^ 1  // 2
+            C = A >> B // 3
+            B = B ^ 5  // 4
+            B = B ^ C  // 5
+            // print(B % 8, terminator: ",")
+            if B % 8 != prog[i] {
+                if i >= maxLen {
+                    maxLen = i
+                    print(String(Ax, radix: 2).paddingToLeft(upTo: 64) +
+                        " (\(i)) \(prog.prefix(i))")
+                }
+                continue aLoop
+            }
+            A = A >> 3
+            if A == 0 {
+                if i == prog.count - 1 {
+                    print(Ax)
+                    break aLoop
+                }
+                continue aLoop
+            }
+        }
+    }
+}
+
+/*
+Loop 1
+B1 = A%8 | B2  | C3   | B4  | B5 = B4^C3 = xxxxx010 | A?
+---------+-----+------+-----+-----------------------+------------
+     000 | 001 | A>>1 | 100 | 100^(A>>1) = xxxxx010 | ...xxxx001x (❌)
+     001 | 000 | A    | 101 | 101^A      = xxxxx010 | ...xxxxx111 (❌)
+     010 | 011 | A>>3 | 110 | 110^(A>>3) = xxxxx010 | ...xx100010
+     011 | 010 | A>>2 | 111 | 111^(A>>2) = xxxxx010 | ...xxx101xx (❌)
+     100 | 101 | A>>5 | 000 | 000^(A>>5) = xxxxx010 | ...010xx100
+     101 | 100 | A>>4 | 001 | 001^(A>>4) = xxxxx010 | ...x011x101
+     110 | 111 | A>>7 | 010 | 010^(A>>7) = xxxxx010 | .000xxxx110
+     111 | 110 | A>>6 | 011 | 011^(A>>6) = xxxxx010 | ..001xxx111
+
+Loop 2
+B1 = A%8 | B2  | C3   | B4  | B5 = B4^C3 = xxxxx100 | A?
+---------+-----+------+-----+-----------------------+---------
+     000 | 001 | A>>1 | 100 | 100^(A>>1) = xxxxx100 | ...xxxx0000
+     001 | 000 | A    | 101 | 101^A      = xxxxx100 | ...xxxxx001
+     010 | 011 | A>>3 | 110 | 110^(A>>3) = xxxxx100 | ...xx010010
+     011 | 010 | A>>2 | 111 | 111^(A>>2) = xxxxx100 | ...xxx011xx (❌)
+     100 | 101 | A>>5 | 000 | 000^(A>>5) = xxxxx100 | 010xx100
+     101 | 100 | A>>4 | 001 | 001^(A>>4) = xxxxx100 | 0011x101
+     110 | 111 | A>>7 | 010 | 010^(A>>7) = xxxxx100 | 0xxxx110
+     111 | 110 | A>>6 | 011 | 011^(A>>6) = xxxxx100 | 01xxx111
+*/