summation of primes

TODO: better algorithm

summation_of_primes/main.go

@@ -0,0 +1,40 @@
+package main
+
+import "fmt"
+
+func main() {
+	sum := 0
+	from := 2
+	count := 0
+	for {
+		if from == 2000000 {
+			break
+		}
+		if IsPrime(from) {
+			fmt.Println("prime:", from)
+			sum += from
+			count++
+		}
+		from++
+	}
+	fmt.Println("sum:", sum, count)
+}
+
+func IsPrime(n int) bool {
+	if n < 2 {
+		return false
+	}
+	if n == 2 {
+		return true
+	}
+	squareRoot := 1
+	for squareRoot*squareRoot < n {
+		squareRoot++
+	}
+	for i := 2; i <= squareRoot; i++ {
+		if n%i == 0 {
+			return false
+		}
+	}
+	return true
+}

summation_of_primes/summation_of_primes_test.go

@@ -0,0 +1,46 @@
+package main
+
+import "testing"
+
+func TestIsPrime(t *testing.T) {
+	tt := []struct {
+		name  string
+		input int
+		want  bool
+	}{
+		{
+			"1",
+			1,
+			false,
+		},
+		{
+			"2",
+			2,
+			true,
+		},
+		{
+			"10",
+			10,
+			false,
+		},
+		{
+			"17",
+			17,
+			true,
+		},
+		{
+			"97",
+			97,
+			true,
+		},
+	}
+
+	for _, tc := range tt {
+		t.Run(tc.name, func(t *testing.T) {
+			got := IsPrime(tc.input)
+			if got != tc.want {
+				t.Errorf("IsPrime(%d)=%v, want %v", tc.input, got, tc.want)
+			}
+		})
+	}
+}