Day 16

AoC21.xcodeproj/project.pbxproj

@@ -27,6 +27,8 @@
 		269BE5CD2762A08800871C85 /* common.swift in Sources */ = {isa = PBXBuildFile; fileRef = 269BE5CB2762A08800871C85 /* common.swift */; };
 		269BE5CE2762A08800871C85 /* common.swift in Sources */ = {isa = PBXBuildFile; fileRef = 269BE5CB2762A08800871C85 /* common.swift */; };
 		269BE5CF2762A08800871C85 /* common.swift in Sources */ = {isa = PBXBuildFile; fileRef = 269BE5CB2762A08800871C85 /* common.swift */; };
+		26EA5DFE276BA670003E0305 /* common.swift in Sources */ = {isa = PBXBuildFile; fileRef = 269BE5CB2762A08800871C85 /* common.swift */; };
+		26EA5E00276BA680003E0305 /* day16.swift in Sources */ = {isa = PBXBuildFile; fileRef = 26EA5DFF276BA680003E0305 /* day16.swift */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXCopyFilesBuildPhase section */
@@ -120,6 +122,15 @@
 			);
 			runOnlyForDeploymentPostprocessing = 1;
 		};
+		26EA5DF5276BA668003E0305 /* CopyFiles */ = {
+			isa = PBXCopyFilesBuildPhase;
+			buildActionMask = 2147483647;
+			dstPath = /usr/share/man/man1/;
+			dstSubfolderSpec = 0;
+			files = (
+			);
+			runOnlyForDeploymentPostprocessing = 1;
+		};
 /* End PBXCopyFilesBuildPhase section */
 
 /* Begin PBXFileReference section */
@@ -144,6 +155,8 @@
 		269BE5C12762A03F00871C85 /* Day9 */ = {isa = PBXFileReference; explicitFileType = "compiled.mach-o.executable"; includeInIndex = 0; path = Day9; sourceTree = BUILT_PRODUCTS_DIR; };
 		269BE5C82762A04F00871C85 /* day9.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = day9.swift; sourceTree = "<group>"; };
 		269BE5CB2762A08800871C85 /* common.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = common.swift; sourceTree = "<group>"; };
+		26EA5DF7276BA668003E0305 /* Day16 */ = {isa = PBXFileReference; explicitFileType = "compiled.mach-o.executable"; includeInIndex = 0; path = Day16; sourceTree = BUILT_PRODUCTS_DIR; };
+		26EA5DFF276BA680003E0305 /* day16.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = day16.swift; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -217,12 +230,20 @@
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
+		26EA5DF4276BA668003E0305 /* Frameworks */ = {
+			isa = PBXFrameworksBuildPhase;
+			buildActionMask = 2147483647;
+			files = (
+			);
+			runOnlyForDeploymentPostprocessing = 0;
+		};
 /* End PBXFrameworksBuildPhase section */
 
 /* Begin PBXGroup section */
 		263BA594275E974800839C92 = {
 			isa = PBXGroup;
 			children = (
+				26EA5DFF276BA680003E0305 /* day16.swift */,
 				26155467276A6D0A00374D18 /* day15.swift */,
 				26155459276A6C2C00374D18 /* day14.swift */,
 				265112962767D16D009B7607 /* day13.swift */,
@@ -251,6 +272,7 @@
 				2651128F2767D15A009B7607 /* Day13 */,
 				26155452276A6C1C00374D18 /* Day14 */,
 				26155460276A6CF700374D18 /* Day15 */,
+				26EA5DF7276BA668003E0305 /* Day16 */,
 			);
 			name = Products;
 			sourceTree = "<group>";
@@ -428,6 +450,23 @@
 			productReference = 269BE5C12762A03F00871C85 /* Day9 */;
 			productType = "com.apple.product-type.tool";
 		};
+		26EA5DF6276BA668003E0305 /* Day16 */ = {
+			isa = PBXNativeTarget;
+			buildConfigurationList = 26EA5DFD276BA668003E0305 /* Build configuration list for PBXNativeTarget "Day16" */;
+			buildPhases = (
+				26EA5DF3276BA668003E0305 /* Sources */,
+				26EA5DF4276BA668003E0305 /* Frameworks */,
+				26EA5DF5276BA668003E0305 /* CopyFiles */,
+			);
+			buildRules = (
+			);
+			dependencies = (
+			);
+			name = Day16;
+			productName = Day16;
+			productReference = 26EA5DF7276BA668003E0305 /* Day16 */;
+			productType = "com.apple.product-type.tool";
+		};
 /* End PBXNativeTarget section */
 
 /* Begin PBXProject section */
@@ -435,7 +474,7 @@
 			isa = PBXProject;
 			attributes = {
 				BuildIndependentTargetsInParallel = 1;
-				LastSwiftUpdateCheck = 1310;
+				LastSwiftUpdateCheck = 1320;
 				LastUpgradeCheck = 1310;
 				TargetAttributes = {
 					26155451276A6C1C00374D18 = {
@@ -475,6 +514,9 @@
 					269BE5C02762A03F00871C85 = {
 						CreatedOnToolsVersion = 13.1;
 					};
+					26EA5DF6276BA668003E0305 = {
+						CreatedOnToolsVersion = 13.2;
+					};
 				};
 			};
 			buildConfigurationList = 263BA598275E974800839C92 /* Build configuration list for PBXProject "AoC21" */;
@@ -500,6 +542,7 @@
 				2651128E2767D15A009B7607 /* Day13 */,
 				26155451276A6C1C00374D18 /* Day14 */,
 				2615545F276A6CF700374D18 /* Day15 */,
+				26EA5DF6276BA668003E0305 /* Day16 */,
 			);
 		};
 /* End PBXProject section */
@@ -595,6 +638,15 @@
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
+		26EA5DF3276BA668003E0305 /* Sources */ = {
+			isa = PBXSourcesBuildPhase;
+			buildActionMask = 2147483647;
+			files = (
+				26EA5DFE276BA670003E0305 /* common.swift in Sources */,
+				26EA5E00276BA680003E0305 /* day16.swift in Sources */,
+			);
+			runOnlyForDeploymentPostprocessing = 0;
+		};
 /* End PBXSourcesBuildPhase section */
 
 /* Begin XCBuildConfiguration section */
@@ -1024,6 +1076,30 @@
 			};
 			name = Release;
 		};
+		26EA5DFB276BA668003E0305 /* Debug */ = {
+			isa = XCBuildConfiguration;
+			buildSettings = {
+				CODE_SIGN_STYLE = Automatic;
+				DEVELOPMENT_TEAM = 722B335UM5;
+				ENABLE_HARDENED_RUNTIME = YES;
+				MACOSX_DEPLOYMENT_TARGET = 12.1;
+				PRODUCT_NAME = "$(TARGET_NAME)";
+				SWIFT_VERSION = 5.0;
+			};
+			name = Debug;
+		};
+		26EA5DFC276BA668003E0305 /* Release */ = {
+			isa = XCBuildConfiguration;
+			buildSettings = {
+				CODE_SIGN_STYLE = Automatic;
+				DEVELOPMENT_TEAM = 722B335UM5;
+				ENABLE_HARDENED_RUNTIME = YES;
+				MACOSX_DEPLOYMENT_TARGET = 12.1;
+				PRODUCT_NAME = "$(TARGET_NAME)";
+				SWIFT_VERSION = 5.0;
+			};
+			name = Release;
+		};
 /* End XCBuildConfiguration section */
 
 /* Begin XCConfigurationList section */
@@ -1126,6 +1202,15 @@
 			defaultConfigurationIsVisible = 0;
 			defaultConfigurationName = Release;
 		};
+		26EA5DFD276BA668003E0305 /* Build configuration list for PBXNativeTarget "Day16" */ = {
+			isa = XCConfigurationList;
+			buildConfigurations = (
+				26EA5DFB276BA668003E0305 /* Debug */,
+				26EA5DFC276BA668003E0305 /* Release */,
+			);
+			defaultConfigurationIsVisible = 0;
+			defaultConfigurationName = Release;
+		};
 /* End XCConfigurationList section */
 	};
 	rootObject = 263BA595275E974800839C92 /* Project object */;

day16.swift

@@ -0,0 +1,131 @@
+@main
+struct Day16: Puzzle {
+    mutating func run() {
+        var start = Cursor.start
+
+        let part2 = packet(at: &start)
+        print("Part 1:", versionSum)
+        print("Part 2:", part2)
+    }
+
+    var versionSum = 0
+
+    mutating func packet(at cursor: inout Cursor) -> UInt64 {
+        let version = getBits(at: &cursor, count: 3)
+        let type = getBits(at: &cursor, count: 3)
+
+        versionSum += Int(version)
+
+        if type == 4 {
+            return literal(at: &cursor)
+        }
+
+        let subPackets = operatorPacket(at: &cursor)
+
+        switch type {
+        case 0: return subPackets.reduce(0, +)
+        case 1: return subPackets.reduce(1, *)
+        case 2: return subPackets.min()!
+        case 3: return subPackets.max()!
+        case 5: return subPackets[0] > subPackets[1] ? 1 : 0
+        case 6: return subPackets[0] < subPackets[1] ? 1 : 0
+        case 7: return subPackets[0] == subPackets[1] ? 1 : 0
+        default: fatalError("Unknown packet type \(type)")
+        }
+
+    }
+
+    func literal(at cursor: inout Cursor) -> UInt64 {
+        var result: UInt64 = 0
+        while getBit(at: &cursor) {
+            result = result << 4 | getBits(at: &cursor, count: 4)
+        }
+        result = result << 4 | getBits(at: &cursor, count: 4)
+        return result
+    }
+
+    mutating func operatorPacket(at cursor: inout Cursor) -> [UInt64] {
+        let type = getBit(at: &cursor)
+        var result: [UInt64] = []
+        if type {
+            let count = getBits(at: &cursor, count: 11)
+            for _ in 0..<count {
+                result.append(packet(at: &cursor))
+            }
+        } else {
+            let length = getBits(at: &cursor, count: 15)
+            let end = cursor.adding(bits: Int(length))
+            while cursor < end {
+                result.append(packet(at: &cursor))
+            }
+        }
+        return result
+    }
+
+
+    struct Cursor: Equatable {
+        var offset: Int
+        var bit: Int
+
+        static let start = Cursor(offset: 0, bit: 0)
+
+        var remainingBits: Int { 4 - bit }
+
+        mutating func skip(_ bits: Int) {
+            bit += bits
+            offset += bit / 4
+            bit = bit % 4
+        }
+
+        func adding(bits: Int) -> Cursor {
+            var result = self
+            result.skip(bits)
+            return result
+        }
+
+        var bitPos: Int {
+            offset * 4 + bit
+        }
+
+        static func < (lhs: Cursor, rhs: Cursor) -> Bool {
+            lhs.bitPos < rhs.bitPos
+        }
+    }
+
+    func getBit(at cursor: inout Cursor) -> Bool {
+        getBits(at: &cursor, count: 1) == 1
+    }
+
+    func getBitRange(_ x: Int, start: Int, count: Int) -> UInt64 {
+        let mask = UInt64((1 << count) - 1)
+        let shift = 4 - count - start
+        precondition(shift >= 0)
+
+        return UInt64(x) >> shift & mask
+    }
+
+    func getBits(at cursor: inout Cursor, count: Int) -> UInt64 {
+        var remaining = count
+        var result: UInt64 = 0
+
+        while remaining > 0 {
+            let take = min(cursor.remainingBits, remaining)
+            let bits = getBitRange(input[cursor.offset], start: cursor.bit, count: take)
+
+            result = result << take | bits
+            remaining -= take
+
+            cursor.bit += take
+            if cursor.bit == 4 {
+                cursor.bit = 0
+                cursor.offset += 1
+            }
+        }
+
+        return result
+    }
+
+    let input = """
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
+""".compactMap { $0.hexDigitValue }
+}