Data commit

Task/Mertens-function/Go/mertens-function.go

@@ -0,0 +1,66 @@
+package main
+
+import "fmt"
+
+func mertens(to int) ([]int, int, int) {
+    if to < 1 {
+        to = 1
+    }
+    merts := make([]int, to+1)
+    primes := []int{2}
+    var sum, zeros, crosses int
+    for i := 1; i <= to; i++ {
+        j := i
+        cp := 0      // counts prime factors
+        spf := false // true if there is a square prime factor
+        for _, p := range primes {
+            if p > j {
+                break
+            }
+            if j%p == 0 {
+                j /= p
+                cp++
+            }
+            if j%p == 0 {
+                spf = true
+                break
+            }
+        }
+        if cp == 0 && i > 2 {
+            cp = 1
+            primes = append(primes, i)
+        }
+        if !spf {
+            if cp%2 == 0 {
+                sum++
+            } else {
+                sum--
+            }
+        }
+        merts[i] = sum
+        if sum == 0 {
+            zeros++
+            if i > 1 && merts[i-1] != 0 {
+                crosses++
+            }
+        }
+    }
+    return merts, zeros, crosses
+}
+
+func main() {
+    merts, zeros, crosses := mertens(1000)
+    fmt.Println("Mertens sequence - First 199 terms:")
+    for i := 0; i < 200; i++ {
+        if i == 0 {
+            fmt.Print("    ")
+            continue
+        }
+        if i%20 == 0 {
+            fmt.Println()
+        }
+        fmt.Printf("  % d", merts[i])
+    }
+    fmt.Println("\n\nEquals zero", zeros, "times between 1 and 1000")
+    fmt.Println("\nCrosses zero", crosses, "times between 1 and 1000")
+}