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Percolation/Bond percolation: Difference between revisions
Add Swift
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Line 1,601:
proportion of grids that percolate p=9/10 : 0 (0.00000)
proportion of grids that percolate p=1 : 0 (0.00000)</pre>
=={{header|Swift}}==
{{trans|C}}
<lang swift>let randMax = 32767.0
let filled = 1
let rightWall = 2
let bottomWall = 4
final class Percolate {
let height: Int
let width: Int
private var grid: [Int]
private var end: Int
init(height: Int, width: Int) {
self.height = height
self.width = width
self.end = width
self.grid = [Int](repeating: 0, count: width * (height + 2))
}
private func fill(at p: Int) -> Bool {
guard grid[p] & filled == 0 else { return false }
grid[p] |= filled
guard p < end else { return true }
return (((grid[p + 0] & bottomWall) == 0) && fill(at: p + width)) ||
(((grid[p + 0] & rightWall) == 0) && fill(at: p + 1)) ||
(((grid[p - 1] & rightWall) == 0) && fill(at: p - 1)) ||
(((grid[p - width] & bottomWall) == 0) && fill(at: p - width))
}
func makeGrid(porosity p: Double) {
grid = [Int](repeating: 0, count: width * (height + 2))
end = width
let thresh = Int(randMax * p)
for i in 0..<width {
grid[i] = bottomWall | rightWall
}
for _ in 0..<height {
for _ in stride(from: width - 1, through: 1, by: -1) {
let r1 = Int.random(in: 0..<Int(randMax)+1)
let r2 = Int.random(in: 0..<Int(randMax)+1)
grid[end] = (r1 < thresh ? bottomWall : 0) | (r2 < thresh ? rightWall : 0)
end += 1
}
let r3 = Int.random(in: 0..<Int(randMax)+1)
grid[end] = rightWall | (r3 < thresh ? bottomWall : 0)
end += 1
}
}
@discardableResult
func percolate() -> Bool {
var i = 0
while i < width && !fill(at: width + i) {
i += 1
}
return i < width
}
func showGrid() {
for _ in 0..<width {
print("+--", terminator: "")
}
print("+")
for i in 0..<height {
print(i == height ? " " : "|", terminator: "")
for j in 0..<width {
print(grid[i * width + j + width] & filled != 0 ? "[]" : " ", terminator: "")
print(grid[i * width + j + width] & rightWall != 0 ? "|" : " ", terminator: "")
}
print()
guard i != height else { return }
for j in 0..<width {
print(grid[i * width + j + width] & bottomWall != 0 ? "+--" : "+ ", terminator: "")
}
print("+")
}
}
}
let p = Percolate(height: 10, width: 10)
p.makeGrid(porosity: 0.5)
p.percolate()
p.showGrid()
print("Running \(p.height) x \(p.width) grid 10,000 times for each porosity")
for factor in 1...10 {
var count = 0
let porosity = Double(factor) / 10.0
for _ in 0..<10_000 {
p.makeGrid(porosity: porosity)
if (p.percolate()) {
count += 1
}
}
print("p = \(porosity): \(Double(count) / 10_000.0)")
}</lang>
{{out}}
<pre>+--+--+--+--+--+--+--+--+--+--+
|[]| | | | | | |
+ + +--+--+ + +--+ + + +
|[] [] | | | |
+--+ +--+--+ +--+--+ +--+ +
| [] [] []| | | |
+ +--+--+ + +--+--+ + + +
| [] []| | |
+--+--+ +--+ + + + +--+ +
| [] [] | | | |
+ +--+--+ +--+--+--+--+ +--+
| | | |[] | | |
+ + +--+ +--+--+--+--+--+--+
| | |[] [] [] | |
+--+--+--+--+--+ + +--+--+ +
| | | |[]| | | |
+ + + + +--+ +--+ + +--+
| | | | [] []| | | |
+--+--+--+--+ +--+--+--+--+ +
| | | [] | | |
+--+--+ +--+ +--+ +--+--+ +
Running 10 x 10 grid 10,000 times for each porosity
p = 0.1: 1.0
p = 0.2: 1.0
p = 0.3: 0.9968
p = 0.4: 0.9125
p = 0.5: 0.4959
p = 0.6: 0.0858
p = 0.7: 0.004
p = 0.8: 0.0
p = 0.9: 0.0
p = 1.0: 0.0</pre>
=={{header|Tcl}}==
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