Data commit

Task/Sphenic-numbers/Go/sphenic-numbers.go

@@ -0,0 +1,59 @@
+package main
+
+import (
+    "fmt"
+    "math"
+    "rcu"
+    "sort"
+)
+
+func main() {
+    const limit = 1000000
+    limit2 := int(math.Cbrt(limit))
+    primes := rcu.Primes(limit / 6)
+    pc := len(primes)
+    var sphenic []int
+    fmt.Println("Sphenic numbers less than 1,000:")
+    for i := 0; i < pc-2; i++ {
+        if primes[i] > limit2 {
+            break
+        }
+        for j := i + 1; j < pc-1; j++ {
+            prod := primes[i] * primes[j]
+            if prod+primes[j+1] >= limit {
+                break
+            }
+            for k := j + 1; k < pc; k++ {
+                res := prod * primes[k]
+                if res >= limit {
+                    break
+                }
+                sphenic = append(sphenic, res)
+            }
+        }
+    }
+    sort.Ints(sphenic)
+    ix := sort.Search(len(sphenic), func(i int) bool { return sphenic[i] >= 1000 })
+    rcu.PrintTable(sphenic[:ix], 15, 3, false)
+    fmt.Println("\nSphenic triplets less than 10,000:")
+    var triplets [][3]int
+    for i := 0; i < len(sphenic)-2; i++ {
+        s := sphenic[i]
+        if sphenic[i+1] == s+1 && sphenic[i+2] == s+2 {
+            triplets = append(triplets, [3]int{s, s + 1, s + 2})
+        }
+    }
+    ix = sort.Search(len(triplets), func(i int) bool { return triplets[i][2] >= 10000 })
+    for i := 0; i < ix; i++ {
+        fmt.Printf("%4d ", triplets[i])
+        if (i+1)%3 == 0 {
+            fmt.Println()
+        }
+    }
+    fmt.Printf("\nThere are %s sphenic numbers less than 1,000,000.\n", rcu.Commatize(len(sphenic)))
+    fmt.Printf("There are %s sphenic triplets less than 1,000,000.\n", rcu.Commatize(len(triplets)))
+    s := sphenic[199999]
+    pf := rcu.PrimeFactors(s)
+    fmt.Printf("The 200,000th sphenic number is %s (%d*%d*%d).\n", rcu.Commatize(s), pf[0], pf[1], pf[2])
+    fmt.Printf("The 5,000th sphenic triplet is %v.\n.", triplets[4999])
+}