Data commit

Task/Permutations/Lua/permutations-1.lua

@@ -0,0 +1,17 @@
+local function permutation(a, n, cb)
+	if n == 0 then
+		cb(a)
+	else
+		for i = 1, n do
+			a[i], a[n] = a[n], a[i]
+			permutation(a, n - 1, cb)
+			a[i], a[n] = a[n], a[i]
+		end
+	end
+end
+
+--Usage
+local function callback(a)
+	print('{'..table.concat(a, ', ')..'}')
+end
+permutation({1,2,3}, 3, callback)

Task/Permutations/Lua/permutations-2.lua

@@ -0,0 +1,31 @@
+-- Iterative version
+function ipermutations(a,b)
+    if a==0 then return end
+    local taken = {} local slots = {}
+    for i=1,a do slots[i]=0 end
+    for i=1,b do taken[i]=false end
+    local index = 1
+    while index > 0 do repeat
+        repeat slots[index] = slots[index] + 1
+        until slots[index] > b or not taken[slots[index]]
+        if slots[index] > b then
+            slots[index] = 0
+            index = index - 1
+            if index > 0 then
+                taken[slots[index]] = false
+            end
+            break
+        else
+            taken[slots[index]] = true
+        end
+        if index == a then
+            for i=1,a do io.write(slots[i]) io.write(" ") end
+            io.write("\n")
+            taken[slots[index]] = false
+            break
+        end
+        index = index + 1
+    until true end
+end
+
+ipermutations(3, 3)

Task/Permutations/Lua/permutations-3.lua

@@ -0,0 +1,41 @@
+#!/usr/bin/env luajit
+-- Iterative version
+local function ipermgen(a,b)
+    if a==0 then return end
+    local taken = {} local slots = {}
+    for i=1,a do slots[i]=0 end
+    for i=1,b do taken[i]=false end
+    local index = 1
+    while index > 0 do repeat
+        repeat slots[index] = slots[index] + 1
+        until slots[index] > b or not taken[slots[index]]
+        if slots[index] > b then
+            slots[index] = 0
+            index = index - 1
+            if index > 0 then
+                taken[slots[index]] = false
+            end
+            break
+        else
+            taken[slots[index]] = true
+        end
+        if index == a then
+			coroutine.yield(slots)
+            taken[slots[index]] = false
+            break
+        end
+        index = index + 1
+    until true end
+end
+local function iperm(a)
+	local co=coroutine.create(function() ipermgen(a,a) end)
+	return function()
+		local code,res=coroutine.resume(co)
+			return res
+		end
+end
+
+local a=arg[1] and tonumber(arg[1]) or 3
+for p in iperm(a) do
+	print(table.concat(p, " "))
+end