linked-list-cycle

Author: DaleSeo

linked-list-cycle/DaleSeo.rs

@@ -0,0 +1,28 @@
+// Definition for singly-linked list.
+#[derive(PartialEq, Eq, Clone, Debug)]
+pub struct ListNode {
+    pub val: i32,
+    pub next: Option<Box<ListNode>>,
+}
+
+// TC: O(n)
+// SC: O(1)
+impl Solution {
+    pub fn has_cycle(head: Option<Box<ListNode>>) -> bool {
+        let mut slow = &head;
+        let mut fast = &head;
+
+        while fast.is_some() && fast.as_ref().unwrap().next.is_some() {
+            slow = &slow.as_ref().unwrap().next;
+            fast = &fast.as_ref().unwrap().next.as_ref().unwrap().next;
+
+            if slow.as_ref().map(|node| node.as_ref() as *const _)
+                == fast.as_ref().map(|node| node.as_ref() as *const _)
+            {
+                return true;
+            }
+        }
+
+        false
+    }
+}