Data commit

Task/Totient-function/Nim/totient-function.nim

@@ -0,0 +1,35 @@
+import strformat
+
+func totient(n: int): int =
+    var tot = n
+    var nn = n
+    var i = 2
+    while i * i <= nn:
+        if nn mod i == 0:
+            while nn mod i == 0:
+                nn = nn div i
+            dec tot, tot div i
+        if i == 2:
+            i = 1
+        inc i, 2
+    if nn > 1:
+        dec tot, tot div nn
+    tot
+
+echo " n    φ   prime"
+echo "---------------"
+var count = 0
+for n in 1..25:
+    let tot = totient(n)
+    let isPrime = n - 1 == tot
+    if isPrime:
+        inc count
+    echo fmt"{n:2}   {tot:2}   {isPrime}"
+echo ""
+echo fmt"Number of primes up to {25:>6} = {count:>4}"
+for n in 26..100_000:
+    let tot = totient(n)
+    if tot == n - 1:
+        inc count
+    if n == 100 or n == 1000 or n mod 10_000 == 0:
+        echo fmt"Number of primes up to {n:>6} = {count:>4}"