lc starting today - 2025-11-30

1 files changed, 84 insertions, 0 deletions

diff --git a/02_add-two-numbers/src/main.rs b/02_add-two-numbers/src/main.rs
new file mode 100644
index 0000000..6b46dbf
--- /dev/null
+++ b/02_add-two-numbers/src/main.rs
@@ -0,0 +1,84 @@
+fn main() {
+    let list1 = Some(Box::new(ListNode {
+        val: 2,
+        next: Some(Box::new(ListNode {
+            val: 4,
+            next: Some(Box::new(ListNode { val: 3, next: None })),
+        })),
+    }));
+
+    let list2 = Some(Box::new(ListNode {
+        val: 5,
+        next: Some(Box::new(ListNode {
+            val: 6,
+            next: Some(Box::new(ListNode { val: 4, next: None })),
+        })),
+    }));
+
+    Solution::add_two_numbers(list1, list2);
+}
+
+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 add_two_numbers(
+        l1: Option<Box<ListNode>>,
+        l2: Option<Box<ListNode>>,
+    ) -> Option<Box<ListNode>> {
+        let ans = Self::double_walker(l1, l2, false);
+        ans
+    }
+
+    fn double_walker(
+        l1: Option<Box<ListNode>>,
+        l2: Option<Box<ListNode>>,
+        carry: bool,
+    ) -> Option<Box<ListNode>> {
+        if let (None, None) = (&l1, &l2) {
+            if carry {
+                return Some(Box::new(ListNode::new(1)));
+            } else {
+                return None;
+            }
+        }
+
+        let mut node = ListNode::new(0);
+
+        if let Some(n1) = &l1 {
+            node.val += n1.val;
+        }
+
+        if let Some(n2) = &l2 {
+            node.val += n2.val;
+        }
+
+        if carry {
+            node.val += 1;
+        }
+
+        node.next = Self::double_walker(
+            l1.and_then(|n| n.next),
+            l2.and_then(|n| n.next),
+            node.val >= 10,
+        );
+
+        if node.val >= 10 {
+            node.val = node.val - 10;
+        }
+
+        Some(Box::new(node))
+    }
+}