Data commit

Task/Achilles-numbers/Go/achilles-numbers.go

@@ -0,0 +1,110 @@
+package main
+
+import (
+    "fmt"
+    "math"
+    "sort"
+)
+
+func totient(n int) int {
+    tot := n
+    i := 2
+    for i*i <= n {
+        if n%i == 0 {
+            for n%i == 0 {
+                n /= i
+            }
+            tot -= tot / i
+        }
+        if i == 2 {
+            i = 1
+        }
+        i += 2
+    }
+    if n > 1 {
+        tot -= tot / n
+    }
+    return tot
+}
+
+var pps = make(map[int]bool)
+
+func getPerfectPowers(maxExp int) {
+    upper := math.Pow(10, float64(maxExp))
+    for i := 2; i <= int(math.Sqrt(upper)); i++ {
+        fi := float64(i)
+        p := fi
+        for {
+            p *= fi
+            if p >= upper {
+                break
+            }
+            pps[int(p)] = true
+        }
+    }
+}
+
+func getAchilles(minExp, maxExp int) map[int]bool {
+    lower := math.Pow(10, float64(minExp))
+    upper := math.Pow(10, float64(maxExp))
+    achilles := make(map[int]bool)
+    for b := 1; b <= int(math.Cbrt(upper)); b++ {
+        b3 := b * b * b
+        for a := 1; a <= int(math.Sqrt(upper)); a++ {
+            p := b3 * a * a
+            if p >= int(upper) {
+                break
+            }
+            if p >= int(lower) {
+                if _, ok := pps[p]; !ok {
+                    achilles[p] = true
+                }
+            }
+        }
+    }
+    return achilles
+}
+
+func main() {
+    maxDigits := 15
+    getPerfectPowers(maxDigits)
+    achillesSet := getAchilles(1, 5) // enough for first 2 parts
+    achilles := make([]int, len(achillesSet))
+    i := 0
+    for k := range achillesSet {
+        achilles[i] = k
+        i++
+    }
+    sort.Ints(achilles)
+
+    fmt.Println("First 50 Achilles numbers:")
+    for i = 0; i < 50; i++ {
+        fmt.Printf("%4d ", achilles[i])
+        if (i+1)%10 == 0 {
+            fmt.Println()
+        }
+    }
+
+    fmt.Println("\nFirst 30 strong Achilles numbers:")
+    var strongAchilles []int
+    count := 0
+    for n := 0; count < 30; n++ {
+        tot := totient(achilles[n])
+        if _, ok := achillesSet[tot]; ok {
+            strongAchilles = append(strongAchilles, achilles[n])
+            count++
+        }
+    }
+    for i = 0; i < 30; i++ {
+        fmt.Printf("%5d ", strongAchilles[i])
+        if (i+1)%10 == 0 {
+            fmt.Println()
+        }
+    }
+
+    fmt.Println("\nNumber of Achilles numbers with:")
+    for d := 2; d <= maxDigits; d++ {
+        ac := len(getAchilles(d-1, d))
+        fmt.Printf("%2d digits: %d\n", d, ac)
+    }
+}