33 lines
678 B
Swift
33 lines
678 B
Swift
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let input = loadData(day: 3).lines()
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/// - returns true if a tree is at that position, false if it is empty
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func get(x: Int, y: Int) -> Bool {
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let line = input[y]
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let index = line.index(line.startIndex, offsetBy: x % line.count)
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return line[index] == "#"
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}
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func calculate(dx: Int, dy: Int) -> Int {
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var x = 0
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var y = 0
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var trees = 0
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while y < input.count {
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if get(x: x, y: y) {
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trees += 1
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}
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x += dx
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y += dy
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}
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return trees
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}
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let trees = calculate(dx: 3, dy: 1)
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print("trees", trees)
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print("combined", calculate(dx: 1, dy: 1) * calculate(dx: 3, dy: 1) * calculate(dx: 5, dy: 1) * calculate(dx: 7, dy: 1) * calculate(dx: 1, dy: 2))
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