LeetCode-in-All
2. Add Two Numbers
Medium
You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order, and each of their nodes contains a single digit. Add the two numbers and return the sum as a linked list.
You may assume the two numbers do not contain any leading zero, except the number 0 itself.
Example 1:
Input: l1 = [2,4,3], l2 = [5,6,4]
Output: [7,0,8]
Explanation: 342 + 465 = 807.
Example 2:
Input: l1 = [0], l2 = [0]
Output: [0]
Example 3:
Input: l1 = [9,9,9,9,9,9,9], l2 = [9,9,9,9]
Output: [8,9,9,9,0,0,0,1]
Constraints:
- The number of nodes in each linked list is in the range
[1, 100]. 0 <= Node.val <= 9- It is guaranteed that the list represents a number that does not have leading zeros.
Solution
type ListNode struct {
Val int
Next *ListNode
}
/**
* Definition for singly-linked list.
* type ListNode struct {
* Val int
* Next *ListNode
* }
*/
func addTwoNumbers(l1 *ListNode, l2 *ListNode) *ListNode {
dummyHead := &ListNode{}
p, q, curr := l1, l2, dummyHead
carry := 0
for p != nil || q != nil {
x, y := 0, 0
if p != nil {
x = p.Val
p = p.Next
}
if q != nil {
y = q.Val
q = q.Next
}
sum := carry + x + y
carry = sum / 10
curr.Next = &ListNode{Val: sum % 10}
curr = curr.Next
}
if carry > 0 {
curr.Next = &ListNode{Val: carry}
}
return dummyHead.Next
}