| # Eulerian tour algorithm https://en.wikipedia.org/wiki/Eulerian_path | |
| def eulerian_tour(root: TreeNode) -> List[TreeNode]: | |
| tour = [] | |
| def dfs(node: TreeNode, depth: int) -> None: | |
| tour.append((node.val, depth)) | |
| if node.left: | |
| dfs(node.left, depth + 1) | |
| tour.append((node.val, depth)) | |
| if node.right: | |
| dfs(node.right, depth + 1) |
| segs ← ⊃,/∘(⍳∘≢,/¨⊂) | |
| segs ← (⊃,/)⍳∘⊃∘⌽∘⍴,/¨⊂ ⍝ works for matrix also | |
| freq ← ((⎕C ⎕A)∘.=⊢) | |
| mseg ← {⎕IO←0 ⋄ (⍳∘≢⍵)∘.{⍺↓⍵},\⍵} ⍝ all subvectors in correct position | |
| bits ← 2∘⊥⍣¯1 | |
| pdf←{ | |
| ⍺←(0 1) | |
| nom←*⍤-2÷⍨*∘2 | |
| denom←0.5*⍨○2 |
Recall that the definition of the Y combinator is
x = f x -- fixed-point
Y f = f (Y f)The simplest recursion is
x = x -- [error: cannot reference a symbol before it is defined]Create a function repeat that takes a function that calls itself.
| bluebird = s (k s) k | |
| blackbird = bluebird bluebird bluebird | |
| bunting = bluebird blackbird bluebird | |
| becard = bluebird dove bluebird | |
| cardinal = starling (dove starling) (kestrel kestrel) | |
| dove = bluebird bluebird | |
| dickcissel = bluebird dove | |
| dovekies = dove dove | |
| eagle = bluebird blackbird |
| q1920 ← {⎕IO←0 ⋄ (⊂⌷⊢)⍵} | |
| q1672 ← ⌈/+/ | |
| q1431 ← {0≤⍺+⍵-⌈/⍵} | |
| q1512 ← +/=/(((⊂∘↑⍸)(∘.<⍨⍳∘≢))⌷⊢) | |
| q1470 ← {,⍉⍵⍴⍨2,2÷⍨⍴⍵} | |
| q0771 ← +/∊jewels ∘.∊ stones | |
| q0414 ← 3⊃(nums[⍒nums] ∪nums), ⌈/nums | |
| q0053 ← ⌈/∊∘.-⍨0,+\nums | |
| q0058 ← ≢⊃¯1↑⊆⍨' '≠s | |
| q0228 ← {∪¨,⌿1 ¯1∘.↑⍵⊆⍨⍳⍨⍵-⍳≢⍵} |
| let todo<'a> : 'a = Unchecked.defaultof<'a> | |
| let print x = printfn $"{x}" |
| open System | |
| let rnd = Random() | |
| let randint<'a> = | |
| print "generating random number" | |
| rnd.Next(0,10) | |
| type Signal = Signal with | |
| member __.Return x = x | |
| member __.Delay (f:unit -> _) = f |
| import scala.util.DynamicVariable | |
| class Signal[T](expr: => T) { | |
| import Signal._ | |
| private var myExpr: () => T = _ | |
| private var myValue: T = _ | |
| private var observers: Set[Signal[_]] = Set() | |
| private var observed: List[Signal[_]] = Nil | |
| update(expr) |