public class MagicSquare {
let sum = 15
//--------------------------
func isMagic(squares: [Int]) -> Bool {
//literally check every row & column if the total equals 15
if ((squares.count == 9) &&
//horizontally
(squares[0] + squares[1] + squares[2] == sum) &&
(squares[3] + squares[4] + squares[5] == sum) &&
(squares[6] + squares[7] + squares[8] == sum) &&
//vertically
(squares[0] + squares[3] + squares[6] == sum) &&
(squares[1] + squares[4] + squares[7] == sum) &&
(squares[2] + squares[5] + squares[8] == sum) &&
//Crossing
(squares[2] + squares[4] + squares[6] == sum) &&
(squares[0] + squares[4] + squares[8] == sum)
) {
return true
} else {
//nope
return false
}
}
//--------------------------
func showSquare(squares: [Int]) {
//Shows the magic square
for index in 0..<squares.count {
if (index==0 || index==3 || index==6) {
//new line
print("\n------------")
}
print(squares[index], terminator: " | ")
}
print(" ");
}
//--------------------------
func swap(squares: [Int], pos1: Int, pos2: Int) -> [Int] {
//Swap inputs
let init1: Int = squares[pos1]
var copy = squares
copy[pos1] = copy[pos2]
copy[pos2] = init1
return copy
}
//--------------------------
func modify(squares: [Int], start: Int, end: Int) {
//Modifies the square using recursion
var copy = squares
if start == end && isMagic(squares: copy) {
//if have checked for magic square and modified every number
showSquare(squares: copy)
} else {
if start <= end {
for index in start...end {
//swap number
copy = swap(squares: copy, pos1: start, pos2: index)
//check again
//recursion with next number
modify(squares: copy, start: start + 1, end: end)
//swap number again
copy = swap(squares: copy, pos1: start, pos2: index)
}
}
}
}
//--------------------------
}
//=============================
//run program
//var intArray = [ 3 , 6 ,9,12,15,18,21, 24,27 ]
var intArray = [ 1 , 2 ,3,4,5,6,7, 8,9 ]
let getSquare = MagicSquare()
getSquare.modify(squares: intArray, start: 0, end: 8)//start index is 0, end index is 8 (not 9)
