2. Add Two Numbers

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.

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

 

解题思路：将每位按照个位数字相加的形式，判断是否需要进位

 

答案：

 

public ListNode addTwoNumbers(ListNode l1, ListNode l2) {

int val1 = l1.val;

int val2 = l2.val;

 

int val = val1+val2;

 

int v = val%10;

int bit = val/10;

 

ListNode l = new ListNode(v);

ListNode next = l;

 

ListNode next1=l1.next,next2=l2.next;

 

while(null != next1 && null != next2 ){

val1 = next1.val;

next1=next1.next;

 

val2 = next2.val;

next2=next2.next;

 

if(1==bit){

val = val1 + val2 + 1;

}else{

val = val1 + val2;

}

 

v = val%10;

bit = val/10;

 

ListNode node = new ListNode(v);

next.next = node;

next = node;

}

 

while(null != next1 ){

val1 = next1.val;

next1=next1.next;

 

if(1==bit){

val = val1 + 1;

}else{

val = val1;

}

 

v = val%10;

bit = val/10;

 

ListNode node = new ListNode(v);

next.next = node;

next = node;

}

 

while(null != next2 ){

val2 = next2.val;

next2=next2.next;

 

if(1==bit){

val = val2 + 1;

}else{

val = val2;

}

 

v = val%10;

bit = val/10;

 

ListNode node = new ListNode(v);

next.next = node;

next = node;

}

 

if(1 == bit){

ListNode node = new ListNode(1);

next.next = node;

}

 

        return l;

    }