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access(all) | ||
struct Tree { | ||
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var left: Tree? | ||
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var right: Tree? | ||
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init(left: Tree?, right: Tree?) { | ||
self.left = left | ||
self.right = right | ||
} | ||
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fun nodeCount(): Int { | ||
return 1 | ||
+ (self.left?.nodeCount() ?? 0) | ||
+ (self.right?.nodeCount() ?? 0) | ||
} | ||
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fun clear() { | ||
if (self.left != nil) { | ||
self.left?.clear() | ||
self.left = nil | ||
self.right?.clear() | ||
self.right = nil | ||
} | ||
} | ||
} | ||
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fun newTree(depth: Int): Tree { | ||
if depth == 0 { | ||
return Tree(left: nil, right: nil) | ||
} | ||
return Tree( | ||
left: newTree(depth: depth - 1), | ||
right: newTree(depth: depth - 1) | ||
) | ||
} | ||
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fun stretch(_ depth: Int) { | ||
log("stretch tree of depth \(depth), check: \(count(depth))") | ||
} | ||
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fun count(_ depth: Int): Int { | ||
let t = newTree(depth: depth) | ||
let c = t.nodeCount() | ||
t.clear() | ||
return c | ||
} | ||
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fun run(_ n: Int) { | ||
let minDepth = 4 | ||
let maxDepth = minDepth + 2 > n ? minDepth + 2 : n | ||
let stretchDepth = maxDepth + 1 | ||
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stretch(stretchDepth) | ||
let longLivedTree = newTree(depth: maxDepth) | ||
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for depth in InclusiveRange(minDepth, maxDepth, step: 2) { | ||
let iterations = 1 << (maxDepth - depth + minDepth) | ||
var sum = 0 | ||
for _ in InclusiveRange(1, iterations, step: 1) { | ||
sum = sum + count(depth) | ||
} | ||
log("\(iterations), trees of depth \(depth), check: \(sum)") | ||
} | ||
let count = longLivedTree.nodeCount() | ||
longLivedTree.clear() | ||
log("long lived tree of depth \(maxDepth), check: \(count)") | ||
} | ||
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fun main() { | ||
run(10) | ||
} |
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fun newArray(repeating value: Int, count: Int): [Int] { | ||
let array: [Int] = [] | ||
for _ in InclusiveRange(0, count-1) { | ||
array.append(value) | ||
} | ||
return array | ||
} | ||
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fun fannkuch(_ n: Int): Int { | ||
let perm = newArray(repeating: 0, count: n) | ||
let count = newArray(repeating: 0, count: n) | ||
let perm1 = newArray(repeating: 0, count: n) | ||
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for j in InclusiveRange(0, n-1) { | ||
perm1[j] = j | ||
} | ||
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var f = 0 | ||
var i = 0 | ||
var k = 0 | ||
var r = 0 | ||
var flips = 0 | ||
var nperm = 0 | ||
var checksum = 0 | ||
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r = n | ||
while r > 0 { | ||
i = 0 | ||
while r != 1 { | ||
count[r-1] = r | ||
r = r - 1 | ||
} | ||
while i < n { | ||
perm[i] = perm1[i] | ||
i = i + 1 | ||
} | ||
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// Count flips and update max and checksum | ||
f = 0 | ||
k = perm[0] | ||
while k != 0 { | ||
i = 0 | ||
while 2*i < k { | ||
let t = perm[i] | ||
perm[i] = perm[k-i] | ||
perm[k-i] = t | ||
i = i + 1 | ||
} | ||
k = perm[0] | ||
f = f + 1 | ||
} | ||
if f > flips { | ||
flips = f | ||
} | ||
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if (nperm & 0x1) == 0 { | ||
checksum = checksum + f | ||
} else { | ||
checksum = checksum - f | ||
} | ||
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// Use incremental change to generate another permutation | ||
var more = true | ||
while more { | ||
if r == n { | ||
log(checksum) | ||
return flips | ||
} | ||
let p0 = perm1[0] | ||
i = 0 | ||
while i < r { | ||
let j = i+1 | ||
perm1[i] = perm1[j] | ||
i = j | ||
} | ||
perm1[r] = p0 | ||
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count[r] = count[r] - 1 | ||
if count[r] > 0 { | ||
more = false | ||
} else { | ||
r = r + 1 | ||
} | ||
} | ||
nperm = nperm + 1 | ||
} | ||
return flips | ||
} | ||
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access(all) | ||
fun main() { | ||
assert(fannkuch(7) == 16) | ||
} |
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fun fib(_ n: Int): Int { | ||
if n == 0 { | ||
return 0 | ||
} | ||
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let f = [0, 1] | ||
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var i = 2 | ||
while i <= n { | ||
f.append(f[i - 1] + f[i - 2]) | ||
i = i + 1 | ||
} | ||
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return f[n] | ||
} | ||
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access(all) | ||
fun main() { | ||
assert(fib(14) == 377) | ||
} |