leetcode 59: Add Two Numbers

Add Two NumbersNov 1 '11

You are given two linked lists representing two non-negative numbers. 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.

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8

 

 

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */
public class Solution {
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        // Start typing your Java solution below
        // DO NOT write main() function
        if(l1==null) return l2;
        if(l2==null) return l1;
        
        int carry = 0;
        int temp = 0;
        
        temp = l1.val + l2.val;
        carry = temp>9 ? 1: 0;
        ListNode head = new ListNode(temp%10);
        l1=l1.next;
        l2=l2.next;
        ListNode p = head;
                
        while( l1!=null && l2!=null) {
            temp = l1.val + l2.val + carry;
            carry = temp>9 ? 1 : 0;
            temp %= 10;
            p.next = new ListNode(temp);
            p = p.next;
            l1 = l1.next;
            l2 = l2.next;
        }
        
        while( l1!=null) {
            temp = l1.val + carry;
            carry = temp>9 ? 1 : 0;
            temp %= 10;
            p.next = new ListNode(temp);
            p = p.next;
            l1 = l1.next;
        }
        
        while( l2!=null) {
            temp = l2.val + carry;
            carry = temp>9 ? 1 : 0;
            temp %= 10;
            p.next = new ListNode(temp);
            p = p.next;
            l2 = l2.next;
        }
        
        if(carry != 0) {
            p.next = new ListNode(carry);
        }
        
        return head;
    }
}