From 2f05268c149baac05761ee3856f6d74e646d4677 Mon Sep 17 00:00:00 2001
From: Amirreza Kheradmand <amir.rezakheradmand.2017@gmail.com>
Date: Fri, 28 Apr 2023 11:33:55 +0330
Subject: [PATCH 1/2] improve isPrime in detection efficiency. Added checks for
 small primes and even numbers in isPrime function. updated timing logic to
 use time.Since method

---
 src/prime.go | 53 +++++++++++++++++++++++++++++-----------------------
 1 file changed, 30 insertions(+), 23 deletions(-)

diff --git a/src/prime.go b/src/prime.go
index bf14248..0609ac0 100644
--- a/src/prime.go
+++ b/src/prime.go
@@ -1,34 +1,41 @@
 package main
 
 import (
-    "fmt"
-    "math"
-    "time"
+	"fmt"
+	"math"
+	"time"
 )
 
 func isPrime(n int) bool {
-    if n <= 1 {
-        return false
-    }
+	if n <= 1 {
+		return false
+	}
 
-    end := int(math.Sqrt(float64(n)))
-    for i := 2; i <= end; i++ {
-        if n%i == 0 {
-            return false
-        }
-    }
-    return true
+	if n == 2 || n == 3 {
+		return true
+	}
+	if n%2 == 0 {
+		return false
+	}
+
+	end := int(math.Sqrt(float64(n)))
+	for i := 3; i <= end; i += 2 {
+		if n%i == 0 {
+			return false
+		}
+	}
+	return true
 }
 
 func main() {
-    start := float64(time.Now(). UnixMilli()) 
-    c := 0
-    for i := 0; i < 9000000; i++ {
-        if isPrime(i) {
-            c++
-        }
-    }
-    fmt.Println(c)
-    end := float64(time.Now().UnixMilli())
-    fmt.Printf("%vms", end-start)
+	start := time.Now()
+	c := 0
+	for i := 0; i < 9000000; i++ {
+		if isPrime(i) {
+			c++
+		}
+	}
+	fmt.Println(c)
+	elapsed := time.Since(start)
+	fmt.Printf("%vms", elapsed.Milliseconds())
 }

From bd460953425b156e8a072f28dc8f154b53f12db1 Mon Sep 17 00:00:00 2001
From: Amirreza Kheradmand <amir.rezakheradmand.2017@gmail.com>
Date: Sat, 29 Apr 2023 10:43:04 +0330
Subject: [PATCH 2/2] new language: Erlang

---
 run.sh        | 10 ++++++++++
 src/prime.erl | 30 ++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)
 create mode 100644 src/prime.erl

diff --git a/run.sh b/run.sh
index 5756d55..4e897ba 100755
--- a/run.sh
+++ b/run.sh
@@ -125,4 +125,14 @@ sleep 5 # cpu cool down
 python3 ./src/prime.py
 echo "" 
 
+echo "*-------------- erlang ---------------*"
+erl -eval 'erlang:display(erlang:system_info(otp_release)), halt().' -noshell
+erlc -o src ./src/prime.erl
 
+sleep 5
+
+erl -pa src -noshell -s prime main -s init stop
+
+rm ./src/prime.beam
+echo ""
+echo ""
diff --git a/src/prime.erl b/src/prime.erl
new file mode 100644
index 0000000..67e259d
--- /dev/null
+++ b/src/prime.erl
@@ -0,0 +1,30 @@
+-module(prime).
+-export([is_prime/1, main/0]).
+
+is_prime(N) when N =< 1 ->
+    false;
+is_prime(N) ->
+    is_prime_helper(N, 2, round(math:sqrt(N))).
+
+is_prime_helper(_, I, End) when I > End ->
+    true;
+is_prime_helper(N, I, End) ->
+    case N rem I of
+        0 -> false;
+        _ -> is_prime_helper(N, I + 1, End)
+    end.
+
+main() ->
+    Start = erlang:system_time(millisecond),
+    C = count_primes(0, 9000000, 0),
+    io:format("~p~n", [C]),
+    End = erlang:system_time(millisecond),
+    io:format("~pms~n", [End - Start]).
+
+count_primes(I, Max, C) when I < Max ->
+    case is_prime(I) of
+        true -> count_primes(I + 1, Max, C + 1);
+        false -> count_primes(I + 1, Max, C)
+    end;
+count_primes(_, _, C) ->
+    C.