Data commit

Task/Arithmetic-numbers/Rust/arithmetic-numbers.rust

@@ -0,0 +1,66 @@
+fn divisor_count_and_sum(mut n: u32) -> (u32, u32) {
+    let mut divisor_count = 1;
+    let mut divisor_sum = 1;
+    let mut power = 2;
+    while (n & 1) == 0 {
+        divisor_count += 1;
+        divisor_sum += power;
+        power <<= 1;
+        n >>= 1;
+    }
+    let mut p = 3;
+    while p * p <= n {
+        let mut count = 1;
+        let mut sum = 1;
+        power = p;
+        while n % p == 0 {
+            count += 1;
+            sum += power;
+            power *= p;
+            n /= p;
+        }
+        divisor_count *= count;
+        divisor_sum *= sum;
+        p += 2;
+    }
+    if n > 1 {
+        divisor_count *= 2;
+        divisor_sum *= n + 1;
+    }
+    (divisor_count, divisor_sum)
+}
+
+fn main() {
+    let mut arithmetic_count = 0;
+    let mut composite_count = 0;
+    let mut n = 1;
+    while arithmetic_count <= 1000000 {
+        let (divisor_count, divisor_sum) = divisor_count_and_sum(n);
+        if divisor_sum % divisor_count != 0 {
+            n += 1;
+            continue;
+        }
+        arithmetic_count += 1;
+        if divisor_count > 2 {
+            composite_count += 1;
+        }
+        if arithmetic_count <= 100 {
+            print!("{:3} ", n);
+            if arithmetic_count % 10 == 0 {
+                println!();
+            }
+        }
+        if arithmetic_count == 1000
+            || arithmetic_count == 10000
+            || arithmetic_count == 100000
+            || arithmetic_count == 1000000
+        {
+            println!("\n{}th arithmetic number is {}", arithmetic_count, n);
+            println!(
+                "Number of composite arithmetic numbers <= {}: {}",
+                n, composite_count
+            );
+        }
+        n += 1;
+    }
+}