Data commit

Task/Van-Eck-sequence/Rust/van-eck-sequence.rust

@@ -0,0 +1,31 @@
+fn van_eck_sequence() -> impl std::iter::Iterator<Item = i32> {
+    let mut index = 0;
+    let mut last_term = 0;
+    let mut last_pos = std::collections::HashMap::new();
+    std::iter::from_fn(move || {
+        let result = last_term;
+        let mut next_term = 0;
+        if let Some(v) = last_pos.get_mut(&last_term) {
+            next_term = index - *v;
+            *v = index;
+        } else {
+            last_pos.insert(last_term, index);
+        }
+        last_term = next_term;
+        index += 1;
+        Some(result)
+    })
+}
+
+fn main() {
+    let mut v = van_eck_sequence().take(1000);
+    println!("First 10 terms of the Van Eck sequence:");
+    for n in v.by_ref().take(10) {
+        print!("{} ", n);
+    }
+    println!("\nTerms 991 to 1000 of the Van Eck sequence:");
+    for n in v.skip(980) {
+        print!("{} ", n);
+    }
+    println!();
+}