题解 | #链表相加(二)#

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */

class Solution {
public:
    /**
     * 
     * @param head1 ListNode类 
     * @param head2 ListNode类 
     * @return ListNode类
     */
    ListNode* reverseList(ListNode* head){
        ListNode* pre = NULL;
        ListNode* temp = head;
        while(temp != NULL){
            ListNode* cur = temp->next;
            temp->next = pre;
            pre = temp;
            temp = cur;
        }
        return pre;
    }
    ListNode* addInList(ListNode* head1, ListNode* head2) {
        // write code here
        ListNode* new1 = reverseList(head1);
        ListNode* new2 = reverseList(head2);
        ListNode* cur1 = new1;
        ListNode* cur2 = new2;
        ListNode* newhead = new ListNode(-1);
        ListNode* cur = newhead;
        int carry = 0, newval;
        while(cur1 != NULL && cur2 != NULL)
        {
            if(cur1==new1&&cur2==new2){
                if((cur1->val + cur2->val)>=10){
                    carry = 1;
                }
                newval = (cur1->val + cur2->val) % 10;
            }else{
                newval = (cur1->val + cur2->val + carry) % 10;
                if((cur1->val + cur2->val + carry) >= 10){
                    carry = 1;
                }
                else
                    carry = 0;
            }
            ListNode* newL = new ListNode(newval);
            cur->next = newL;
            cur = newL;
            cur1 = cur1->next;
            cur2 = cur2->next;
        }
        while(cur1 != NULL){
            newval = (cur1->val + carry) % 10;
            if((cur1->val + carry) >= 10){
                    carry = 1;
                }
                else
                    carry = 0;
            ListNode* newL = new ListNode(newval);
            cur->next = newL;
            cur = newL;
            cur1 = cur1->next;
        }
        while(cur2 != NULL){
            newval = (cur2->val + carry) % 10;
            if((cur2->val + carry) >= 10){
                    carry = 1;
                }
                else
                    carry = 0;
            ListNode* newL = new ListNode(newval);
            cur->next = newL;
            cur = newL;
            cur2 = cur2->next;
        }
        if(carry == 1){
            ListNode* newL = new ListNode(carry);
            cur->next = newL;
        }
        newhead = newhead->next;
        return reverseList(newhead);
    }
};