feat: 23_merge_k_sorted_lists

23_merge_k_sorted_lists/Cargo.lock

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

23_merge_k_sorted_lists/Cargo.toml

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

23_merge_k_sorted_lists/src/lib.rs

@@ -0,0 +1,62 @@
+#[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 }
+    }
+}
+
+#[derive(Eq)]
+struct List {
+    head: Box<ListNode>,
+}
+
+impl PartialEq for List {
+    fn eq(&self, other: &Self) -> bool {
+        self.head.val == other.head.val
+    }
+}
+
+impl Ord for List {
+    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
+        other.head.val.cmp(&self.head.val)
+    }
+}
+
+impl PartialOrd for List {
+    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+pub struct Solution;
+
+impl Solution {
+    pub fn merge_k_lists(lists: Vec<Option<Box<ListNode>>>) -> Option<Box<ListNode>> {
+        let mut result_head = None;
+        let mut result = &mut result_head;
+
+        let mut heap = std::collections::BinaryHeap::<List>::new();
+        for l in lists {
+            if let Some(head) = l {
+                heap.push(List { head: head });
+            }
+        }
+
+        while let Some(top) = heap.pop() {
+            *result = Some(Box::new(ListNode::new(top.head.val)));
+            result = &mut result.as_mut().unwrap().next;
+
+            if let Some(new_top_head) = top.head.next {
+                heap.push(List { head: new_top_head });
+            }
+        }
+
+        result_head
+    }
+}