Add 2015

2015/Day11.playground/Contents.swift

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+extension String {
+    func increment() -> String {
+        var ascii = map { $0.asciiValue! }
+
+        var carry: UInt8 = 0
+        for index in ascii.indices.reversed() {
+            let next = ascii[index] + 1
+            if next > UInt8(ascii: "z") {
+                carry = 1
+                ascii[index] = UInt8(ascii: "a")
+            } else {
+                ascii[index] = next
+                carry = 0
+            }
+
+            if carry == 0 {
+                break
+            }
+        }
+
+        if carry != 0 {
+            ascii.insert(UInt8(ascii: "a") + carry - 1, at: 0)
+        }
+
+        return String(ascii.map { Character(UnicodeScalar($0)) })
+    }
+
+    var isValid: Bool {
+        containsStraight &&
+            !containsForbidden &&
+            containsTwoPair
+    }
+
+    var containsForbidden: Bool {
+        contains { $0 == "i" || $0 == "o" || $0 == "l" }
+    }
+
+    var containsStraight: Bool {
+        for i in indices.dropLast(2) {
+            let next = index(after: i)
+            let next2 = index(after: next)
+
+            let value = self.unicodeScalars[i].value
+            let value2 = UnicodeScalar(value + 1)
+            let value3 = UnicodeScalar(value + 2)
+
+            if self.unicodeScalars[next] == value2 && self.unicodeScalars[next2] == value3 {
+                return true
+            }
+        }
+        return false
+    }
+
+    var containsTwoPair: Bool {
+        var firstPair: Character? = nil
+        for i in indices.dropLast() {
+            let next = index(after: i)
+
+            guard self[i] == self[next] else { continue }
+
+            if firstPair == nil {
+                firstPair = self[i]
+            } else if firstPair != self[i] {
+                return true
+            }
+
+        }
+        return false
+    }
+}
+
+
+let start = "hxbxwxba"
+
+var password = start
+repeat {
+    password = password.increment()
+} while !password.isValid
+password
+

2015/Day11.playground/contents.xcplayground

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+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='ios' buildActiveScheme='true' importAppTypes='true'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>

2015/Day11.playground/playground.xcworkspace/contents.xcworkspacedata

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+<?xml version="1.0" encoding="UTF-8"?>
+<Workspace
+   version = "1.0">
+   <FileRef
+      location = "group:">
+   </FileRef>
+</Workspace>

2015/Day11.playground/timeline.xctimeline

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+<?xml version="1.0" encoding="UTF-8"?>
+<Timeline
+   version = "3.0">
+   <TimelineItems>
+   </TimelineItems>
+</Timeline>