feat: add initial implementation of insert_greatest_common_divisors function with ListNode struct

2807_insert_greatest_common_divisors_in_linked_list/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "insert_greatest_common_divisors_in_linked_list"
+version = "0.1.0"

2807_insert_greatest_common_divisors_in_linked_list/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "insert_greatest_common_divisors_in_linked_list"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]

2807_insert_greatest_common_divisors_in_linked_list/src/main.rs

@@ -0,0 +1,63 @@
+fn main() {
+    println!("{}", Solution::gcd(10, 25));
+}
+
+struct Solution;
+
+#[derive(PartialEq, Eq, Clone, Debug)]
+pub struct ListNode {
+    pub val: i32,
+    pub next: Option<Box<ListNode>>,
+}
+
+impl ListNode {
+    #[inline]
+    fn new(val: i32) -> Self {
+        ListNode { next: None, val }
+    }
+}
+
+impl Solution {
+    pub fn insert_greatest_common_divisors(
+        mut head: Option<Box<ListNode>>,
+    ) -> Option<Box<ListNode>> {
+        let mut current = &mut head;
+
+        while let Some(node) = current {
+            if let Some(next_node) = &node.next {
+                let a = node.val;
+                let b = next_node.val;
+                let gcd = Solution::gcd(a, b);
+
+                let next = node.next.take();
+                node.next = Some(Box::new(ListNode { val: gcd, next }));
+
+                current = &mut node.next.as_mut().unwrap().next;
+            } else {
+                break;
+            }
+        }
+
+        head
+    }
+
+    fn gcd(mut a: i32, mut b: i32) -> i32 {
+        if a > b {
+            let tmp = a;
+            a = b;
+            b = tmp;
+        }
+
+        loop {
+            let rem = b % a;
+            b = a;
+            a = rem;
+
+            if rem == 0 {
+                break;
+            }
+        }
+
+        b
+    }
+}