Data commit

Task/Stern-Brocot-sequence/Lua/stern-brocot-sequence.lua

@@ -0,0 +1,49 @@
+-- Task 1
+function sternBrocot (n)
+    local sbList, pos, c = {1, 1}, 2
+    repeat
+        c = sbList[pos]
+        table.insert(sbList, c + sbList[pos - 1])
+        table.insert(sbList, c)
+        pos = pos + 1
+    until #sbList >= n
+    return sbList
+end
+
+-- Return index in table 't' of first value matching 'v'
+function findFirst (t, v)
+    for key, value in pairs(t) do
+        if v then
+            if value == v then return key end
+        else
+            if value ~= 0 then return key end
+        end
+    end
+    return nil
+end
+
+-- Return greatest common divisor of 'x' and 'y'
+function gcd (x, y)
+    if y == 0 then
+        return math.abs(x)
+    else
+        return gcd(y, x % y)
+    end
+end
+
+-- Check GCD of adjacent values in 't' up to 1000 is always 1
+function task5 (t)
+    for pos = 1, 1000 do
+        if gcd(t[pos], t[pos + 1]) ~= 1 then return "FAIL" end
+    end
+    return "PASS"
+end
+
+-- Main procedure
+local sb = sternBrocot(10000)
+io.write("Task 2: ")
+for n = 1, 15 do io.write(sb[n] .. " ") end
+print("\n\nTask 3:")
+for i = 1, 10 do print("\t" .. i, findFirst(sb, i)) end
+print("\nTask 4: " .. findFirst(sb, 100))
+print("\nTask 5: " .. task5(sb))