两数相加

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leetcode: 两数相加

对于链表长度头部未知的，可在头部前多设一个节点来快速获取

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class Solution {
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        ListNode temList1,temList2,newList,newTemList;
        temList1 = l1;
        temList2 = l2;
        int carryBit = 0, newBit = 0;
        newList = new ListNode(0);
        newTemList = newList;
        while(true){
            if(temList1 == null){
                while(temList2 != null){
                    newBit = temList2.val + carryBit;
                    if(newBit > 9){
                        carryBit = 1;
                        newBit = newBit - 10;
                    }else{
                        carryBit = 0;
                    }
                    newTemList.next = new ListNode(newBit);
                    newTemList = newTemList.next;
                    temList2 = temList2.next;
                }
                break;
            }
            if(temList2 == null){
                while(temList1 != null){
                    newBit = temList1.val + carryBit;
                    if(newBit > 9){
                        carryBit = 1;
                        newBit = newBit - 10;
                    }else{
                        carryBit = 0;
                    }
                    newTemList.next = new ListNode(newBit);
                    newTemList = newTemList.next;
                    temList1 = temList1.next;
                }
                break;
            }
            newBit = temList1.val + temList2.val + carryBit;
            if(newBit > 9){
                carryBit = 1;
                newBit = newBit - 10;
            }
            else{
                carryBit = 0;
            }
            newTemList.next = new ListNode(newBit);
            newTemList = newTemList.next;
            temList1 = temList1.next;
            temList2 = temList2.next;
        }
        if(carryBit == 1){
            newTemList.next = new ListNode(1);
        }
        return newList.next;
    }
    
}