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 contain a single digit. Add the two numbers and return it as a linked list.
You may assume the two numbers do not contain any leading zero, except the number 0 itself.
Example
Input: (2 -> 4 -> 3) + (5 -> 6 -> 4) Output: 7 -> 0 -> 8 Explanation: 342 + 465 = 807.
/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode(int x) { val = x; }
* }
*/
class Solution {
public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
// save result node
ListNode resNode = new ListNode(0);
// carry bit flag
boolean isCarryBit = false;
// position flag
boolean isFirstIndex = true;
// temp node
ListNode tempNode = resNode;
// iterator node
while(l1 != null || l2 != null) {
int val1 = l1 != null ? l1.val : 0;
int val2 = l2 != null ? l2.val : 0;
// sum digit
int sum = val1 + val2;
int currentVal = (sum + (isCarryBit ? 1 : 0)) % 10;
// crray bit handle
isCarryBit = ((sum + (isCarryBit ? 1 : 0)) >= 10 ? true : false);
if(isFirstIndex) {
resNode.val = currentVal;
} else {
tempNode.next = new ListNode(currentVal);
tempNode = tempNode.next;
}
isFirstIndex = false;
// evalution
if(l1 != null){
l1 = l1.next;
}
if(l2 != null){
l2 = l2.next;
}
}
// carry bit
if(isCarryBit){
tempNode.next = new ListNode(1);
}
// return result node
return resNode;
}
}