add new solutions

solutions/0/q23/solution.go

@@ -0,0 +1,52 @@
+package q23
+
+import "container/heap"
+
+type ListNode struct {
+	Val  int
+	Next *ListNode
+}
+
+type MinNodeHp []*ListNode
+
+func (m *MinNodeHp) Len() int               { return len(*m) }
+func (m *MinNodeHp) Less(i int, j int) bool { return (*m)[i].Val < (*m)[j].Val }
+func (m *MinNodeHp) Push(x any)             { *m = append(*m, x.(*ListNode)) }
+func (m *MinNodeHp) Swap(i int, j int)      { (*m)[i], (*m)[j] = (*m)[j], (*m)[i] }
+
+func (m *MinNodeHp) Pop() any {
+	*m = (*m)[:len(*m)-1]
+	return nil
+}
+
+var _ heap.Interface = &MinNodeHp{}
+
+func mergeKLists(lists []*ListNode) *ListNode {
+	hp := make(MinNodeHp, 0, len(lists))
+	for i := range lists {
+		if lists[i] != nil {
+			hp = append(hp, lists[i])
+		}
+	}
+	heap.Init(&hp)
+
+	head := &ListNode{}
+	tail := head
+
+	for len(hp) > 0 {
+		tail.Next = hp[0]
+		tail = tail.Next
+
+		hp[0] = hp[0].Next
+		if hp[0] == nil {
+			heap.Remove(&hp, 0)
+		} else {
+			heap.Fix(&hp, 0)
+		}
+	}
+
+	tail.Next = nil
+	return head.Next
+}
+
+var _ = mergeKLists