g0001_0100.s0002_add_two_numbers.solution.go Maven / Gradle / Ivy

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104 LeetCode algorithm problem solutions

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package s0002_add_two_numbers

// #Medium #Top_100_Liked_Questions #Top_Interview_Questions #Math #Linked_List #Recursion
// #Data_Structure_II_Day_10_Linked_List #Programming_Skills_II_Day_15
// #Big_O_Time_O(max(N,M))_Space_O(max(N,M)) #2024_03_05_Time_4_ms_(84.60%)_Space_4.4_MB_(47.97%)

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
}