1 files changed, 118 insertions, 0 deletions
diff --git a/reversenumber/main.go b/reversenumber/main.go
new file mode 100644
index 0000000..1a4f5ba
--- /dev/null
+++ b/reversenumber/main.go
@@ -0,0 +1,118 @@
+package main
+
+import "fmt"
+
+type ListNode struct {
+	Val  int
+	Next *ListNode
+}
+
+func addTwoNumbers(l1 *ListNode, l2 *ListNode) *ListNode {
+	r1 := &ListNode{
+		Val: l1.Val,
+	}
+	r2 := &ListNode{
+		Val: l2.Val,
+	}
+
+	l1l := 0
+	l2l := 0
+
+	for {
+		if l1 != nil {
+			l1l += 1
+			r1n := r1
+			r1 = &ListNode{
+				Val:  l1.Val,
+				Next: r1n,
+			}
+			l1 = l1.Next
+		}
+
+		if l2 != nil {
+			l2l += 1
+			r2n := r2
+			r2 = &ListNode{
+				Val:  l2.Val,
+				Next: r2n,
+			}
+			l2 = l2.Next
+		}
+
+		if l1 == nil && l2 == nil {
+			break
+		}
+	}
+
+	var output, input *ListNode
+	if l1l > l2l {
+		output = r1
+		input = r2
+	} else {
+		output = r2
+		input = r2
+	}
+
+	carry := 0
+	var prev *ListNode
+	for {
+		sum := output.Val + carry
+		if input != nil {
+			sum = sum + input.Val
+			input = input.Next
+		}
+
+		carry = sum / 10
+		next := output.Next
+		output.Val = sum % 10
+		output.Next = prev
+		prev = output
+
+		if next == nil {
+			break
+		}
+		output = next
+	}
+
+	return output
+}
+
+func makeList(list []int) *ListNode {
+	output := &ListNode{
+		Val:  list[0],
+		Next: nil,
+	}
+	current := output
+	for _, n := range list[1:] {
+		node := &ListNode{
+			Val: n,
+		}
+		current.Next = node
+		current = node
+	}
+
+	return output
+}
+
+func printList(node *ListNode) {
+	for {
+		if node == nil {
+			break
+		}
+
+		fmt.Print(node.Val)
+		node = node.Next
+	}
+	fmt.Println()
+}
+
+func main() {
+	// Input: l1 = [9,9,9,9,9,9,9], l2 = [9,9,9,9]
+	// Output: [8,9,9,9,0,0,0,1]
+	l1 := makeList([]int{9, 9, 9, 9, 9, 9, 9})
+	l2 := makeList([]int{9, 9, 9, 9})
+	printList(l1)
+	printList(l2)
+
+	printList(addTwoNumbers(l1, l2))
+}