Data commit

Task/Hofstadter-Figure-Figure-sequences/Go/hofstadter-figure-figure-sequences-1.go

@@ -0,0 +1,56 @@
+package main
+
+import "fmt"
+
+var ffr, ffs func(int) int
+
+// The point of the init function is to encapsulate r and s.  If you are
+// not concerned about that or do not want that, r and s can be variables at
+// package level and ffr and ffs can be ordinary functions at package level.
+func init() {
+    // task 1, 2
+    r := []int{0, 1}
+    s := []int{0, 2}
+
+    ffr = func(n int) int {
+        for len(r) <= n {
+            nrk := len(r) - 1       // last n for which r(n) is known
+            rNxt := r[nrk] + s[nrk] // next value of r:  r(nrk+1)
+            r = append(r, rNxt)     // extend sequence r by one element
+            for sn := r[nrk] + 2; sn < rNxt; sn++ {
+                s = append(s, sn)   // extend sequence s up to rNext
+            }
+            s = append(s, rNxt+1)   // extend sequence s one past rNext
+        }
+        return r[n]
+    }
+
+    ffs = func(n int) int {
+        for len(s) <= n {
+            ffr(len(r))
+        }
+        return s[n]
+    }
+}
+
+func main() {
+    // task 3
+    for n := 1; n <= 10; n++ {
+        fmt.Printf("r(%d): %d\n", n, ffr(n))
+    }
+    // task 4
+    var found [1001]int
+    for n := 1; n <= 40; n++ {
+        found[ffr(n)]++
+    }
+    for n := 1; n <= 960; n++ {
+        found[ffs(n)]++
+    }
+    for i := 1; i <= 1000; i++ {
+        if found[i] != 1 {
+            fmt.Println("task 4: FAIL")
+            return
+        }
+    }
+    fmt.Println("task 4: PASS")
+}

Task/Hofstadter-Figure-Figure-sequences/Go/hofstadter-figure-figure-sequences-2.go

@@ -0,0 +1,49 @@
+package main
+import "fmt"
+
+type xint int64
+func R() (func() (xint)) {
+	r, s := xint(0), func() (xint) (nil)
+	return func() (xint) {
+		switch {
+		case r < 1: r = 1
+		case r < 3: r = 3
+		default:
+			if s == nil {
+				s = S()
+				s()
+			}
+			r += s()
+		}
+		if r < 0 { panic("r overflow") }
+		return r
+	}
+}
+
+func S() (func() (xint)) {
+	s, r1, r := xint(0), xint(0), func() (xint) (nil)
+	return func() (xint) {
+		if s < 2 {
+			s = 2
+		} else {
+			if r == nil {
+				r = R()
+				r()
+				r1 = r()
+			}
+			s++
+			if s >  r1 { r1 = r() }
+			if s == r1 { s++ }
+		}
+		if s < 0 { panic("s overflow") }
+		return s
+	}
+}
+
+func main() {
+	r, sum := R(), xint(0)
+	for i := 0; i < 10000000; i++ {
+		sum += r()
+	}
+	fmt.Println(sum)
+}