incomplete

.gitignore

@@ -1,3 +1,5 @@
+.DS_Store
+
 # Xcode
 #
 build/

HWFrom1-17-16(Lists and Sorts).playground/Contents.swift

@@ -2,25 +2,170 @@
 
 import UIKit
 
-var str = "Hello, playground"
-
 /*
 
 
 Work on your solutions here.
 
 Link: https://docs.google.com/document/d/1INvOynuggw69yLRNg3y-TPwBiYb3lQZQiFUOxZKBwsY/edit#heading=h.za36ai6n5fth
 
-1) 
-
-
-
-2) 
-
-
-
-3)
-
+1) */
+
+func sudokuSpaceOptions(board: [[Int?]], x: Int, y: Int) -> [Int] {
+
+    // for our purposes x is the horizontal axis and y the vertical
+    // for this to make sense with the visual layout of the array of arrays
+    // we need to index the numbers like so: number[y][x]
+
+    //check if !nil
+    if board[y][x] != nil {
+
+        // if !nil return the number that is already there as the single member of
+        // the return array
+        return [board[y][x]!]
+    }
+
+    var possibilities: Set = Set([1, 2, 3, 4, 5, 6, 7, 8, 9])
+
+    // check column
+    for i in 0...8 {
+
+        if board[i][x] != nil {
+
+            // exclude numbers in column
+            possibilities.remove(board[i][x]!)
+        }
+    }
+
+    // check row
+    for i in 0...8 {
+
+        // exclude numbers in row
+        if board[y][i] != nil {
+
+            possibilities.remove(board[y][i]!)
+        }
+    }
+
+    let indices: [[Int?]] = [[0, 2], [3, 5], [6, 8]]
+    var xSquareBounds: [Int?] = [nil, nil]
+    var ySquareBounds: [Int?] = [nil, nil]
+
+    // figure out the square bounds
+    for numArray in indices {
+
+        if (x >= numArray[0] && x <= numArray[1]) {
+
+            xSquareBounds = numArray
+        }
+        if (y >= numArray[0] && y <= numArray[1]) {
+
+            ySquareBounds = numArray
+        }
+    }
+
+    // check square
+    for i in ySquareBounds[0]!...ySquareBounds[1]! {
+
+        for j in xSquareBounds[0]!...xSquareBounds[1]! {
+
+            if board[i][j] != nil {
+
+                // exclude numbers in square
+                possibilities.remove(board[i][j]!)
+            }
+        }
+    }
+
+    return Array(possibilities)
+
+}
+
+var sudokuBoard: [[Int?]] = [
+
+    [5  , nil, 8  , nil, 7  , 3  , 1  , 9  , nil],
+    [9  , nil, nil, 6  , nil, nil, 4  , nil, 8  ],
+    [nil, nil, nil, 9  , nil, 8  , nil, 3  , 5  ],
+    [nil, 7  , nil, nil, nil, nil, nil, 6  , nil],
+    [nil, nil, 2  , nil, nil, nil, 9  , nil, nil],
+    [nil, 1  , nil, nil, nil, nil, nil, 8  , nil],
+    [1  , 9  , nil, 3  , nil, 6  , nil, nil, nil],
+    [2  , nil, 3  , nil, nil, 7  , nil, nil, 9  ],
+    [nil, 8  , 7  , 1  , 9  , nil, 3  , nil, 4  ]]
+
+print(sudokuSpaceOptions(sudokuBoard, x: 2, y: 6))
+print(sudokuSpaceOptions(sudokuBoard, x: 2, y: 0))
 
+/*
+2) */
+
+func rotateMatrixByNinetyDegrees(matrix: [[Int]]) -> [[Int]] {
+
+    // create an array of the same dimensions with all zeroes
+    var rotated = [[Int]](count: matrix.count, repeatedValue: [Int](count: matrix[0].count, repeatedValue: 0))
+
+    for i in 0..<matrix.count {
+
+        for j in 0..<matrix[i].count {
+
+            // replace the default zeroes with the rotated values according to the formula
+            rotated[j][matrix.count - 1 - i] = matrix[i][j]
+        }
+    }
+
+    return rotated
+}
+
+let test = [[1,2,3,4],
+            [5,6,7,8],
+            [9,0,1,2],
+            [3,4,5,6]]
+
+let test2 = [[1,2,3,4,0],
+            [5,6,7,8,0],
+            [9,0,1,2,0],
+            [3,4,5,6,0],
+            [7,8,9,0,0]]
+
+print(rotateMatrixByNinetyDegrees(test))
+print(rotateMatrixByNinetyDegrees(test2))
 
-*/
+/*
+3) */
+
+func sortFourElements(inout nums: [Int]) -> [Int] {
+
+    var temp: Int
+    let indices = [[0,1], [2,3], [0,2], [1,3], [1,2]]
+
+    for i in 0..<indices.count {
+
+        if nums[indices[i][0]] > nums[indices[i][1]] {
+
+            temp = nums[indices[i][0]]
+            nums[indices[i][0]] = nums[indices[i][1]]
+            nums[indices[i][1]] = temp
+        }
+    }
+
+    return nums
+
+}
+
+var nums  = [4, 3, 2, 1]
+var nums2 = [4, 3, 1, 2]
+var nums3 = [4, 2, 1, 3]
+var nums4 = [2, 4, 3, 1]
+var nums5 = [3, 4, 1, 2]
+var nums6 = [3, 4, 2, 1]
+var nums7 = [2, 3, 1, 4]
+var nums8 = [3, 2, 4, 1]
+
+print(sortFourElements(&nums))
+print(sortFourElements(&nums2))
+print(sortFourElements(&nums3))
+print(sortFourElements(&nums4))
+print(sortFourElements(&nums5))
+print(sortFourElements(&nums6))
+print(sortFourElements(&nums7))
+print(sortFourElements(&nums8))

HWFrom1-17-16(Lists and Sorts).playground/contents.xcplayground

@@ -1,4 +1,4 @@
 <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
-<playground version='5.0' target-platform='ios'>
+<playground version='5.0' target-platform='ios' executeOnSourceChanges='false'>
     <timeline fileName='timeline.xctimeline'/>
 </playground>

HWFrom1-24(Recursion).playground/Contents.swift

@@ -1,25 +1,50 @@
 /*
-
-
 Homework link: https://docs.google.com/document/d/1INvOynuggw69yLRNg3y-TPwBiYb3lQZQiFUOxZKBwsY/edit#heading=h.za36ai6n5fth
-
-
-
 */
 
 
+import Foundation
 
 //Question 1
 
-
-
-
-
+func fib(n: Int) -> Int {
+
+    var a = 1
+    var b = 1
+
+    for _ in 0..<n {
+        let t = a
+        a = b
+        b = t + b
+    }
+    return b
+}
 
 //Question 2
 
-
-
-
-
-//Question 3
+var stepNum = 0
+func tryStep() -> Int {
+    let stepCount = Int(arc4random_uniform(3)) - 1
+    stepNum += stepCount;
+    switch(stepCount) {
+    case -1: print("Ouch \(stepNum)")
+    case 1: print("Yay  \(stepNum)")
+    default: print("Beep \(stepNum)")
+    }
+    return stepCount
+}
+
+func stepUp() {
+
+    switch tryStep() {
+    case 1:
+        return
+    case -1:
+        stepUp()
+        stepUp()
+    default:
+        stepUp()
+    }
+}
+
+//Question 3

HWFrom1-24(Recursion).playground/contents.xcplayground

@@ -1,4 +1,4 @@
 <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
-<playground version='5.0' target-platform='ios'>
+<playground version='5.0' target-platform='ios' executeOnSourceChanges='false'>
     <timeline fileName='timeline.xctimeline'/>
 </playground>