Data commit

Task/Blum-integer/Go/blum-integer.go

@@ -0,0 +1,70 @@
+package main
+
+import (
+    "fmt"
+    "rcu"
+)
+
+var inc = []int{4, 2, 4, 2, 4, 6, 2, 6}
+
+// Assumes n is odd.
+func firstPrimeFactor(n int) int {
+    if n == 1 {
+        return 1
+    }
+    if n%3 == 0 {
+        return 3
+    }
+    if n%5 == 0 {
+        return 5
+    }
+    for k, i := 7, 0; k*k <= n; {
+        if n%k == 0 {
+            return k
+        } else {
+            k += inc[i]
+            i = (i + 1) % 8
+        }
+    }
+    return n
+}
+
+func main() {
+    blum := make([]int, 50)
+    bc := 0
+    counts := make([]int, 4)
+    i := 1
+    for {
+        p := firstPrimeFactor(i)
+        if p%4 == 3 {
+            q := i / p
+            if q != p && q%4 == 3 && rcu.IsPrime(q) {
+                if bc < 50 {
+                    blum[bc] = i
+                }
+                counts[i%10/3]++
+                bc++
+                if bc == 50 {
+                    fmt.Println("First 50 Blum integers:")
+                    rcu.PrintTable(blum, 10, 3, false)
+                    fmt.Println()
+                } else if bc == 26828 || bc%100000 == 0 {
+                    fmt.Printf("The %7sth Blum integer is: %9s\n", rcu.Commatize(bc), rcu.Commatize(i))
+                    if bc == 400000 {
+                        fmt.Println("\n% distribution of the first 400,000 Blum integers:")
+                        digits := []int{1, 3, 7, 9}
+                        for j := 0; j < 4; j++ {
+                            fmt.Printf("  %6.3f%% end in %d\n", float64(counts[j])/4000, digits[j])
+                        }
+                        return
+                    }
+                }
+            }
+        }
+        if i%5 == 3 {
+            i += 4
+        } else {
+            i += 2
+        }
+    }
+}