2. Add Two Numbers

最新推荐文章于 2021-12-02 14:05:46 发布

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本文介绍了一种使用链表表示非负整数并实现加法运算的算法。通过将两个链表逆序存储的数字相加，返回一个新的链表表示的和。文章详细解释了算法流程，包括处理进位和不同长度链表的加法。

2. Add Two Numbers

Medium

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.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
    	stack<int> t1,t2;//将长链表保存在l1，短链表保存在l2
        ListNode* k1;
        ListNode* k2;
        k1=l1;
        k2=l2;
    	while(k1!=NULL){
    		t1.push(k1->val);
    		k1=k1->next;
    	}
    	while(k2!=NULL){
    		t2.push(k2->val);
    		k2=k2->next;
    	}
    	ListNode* temp;
    	if(t2.size()>t1.size()){
    		temp=l1;
    		l1=l2;
    		l2=temp;
    	}
    	ListNode* head=l1;
    	int c=0;
        //遍历链表进行加运算，同时保存进一在c中
    	while(l1!=NULL){
            if(l2!=NULL&&l1!=NULL){
                l1->val=l1->val+l2->val+c;
    		    if(l1->val>9){
    			    l1->val=l1->val-10;
    			    c=1;
    		    }else{
    			    c=0;
    		    }
                if(l1->next==NULL) break;
                l1=l1->next;
    		    l2=l2->next;
            }else if(l2==NULL&&l1!=NULL){
                l1->val=l1->val+c;
    		    if(l1->val>9){
    			    l1->val=l1->val-10;
    			    c=1;
    		    }else{
    			    c=0;
    		    }
                if(l1->next==NULL) break;
                l1=l1->next;
            } 
    	}
        if(c!=0){
            ListNode* tmp=new ListNode(0);
            tmp->val=c;
            l1->next=tmp;
            l1=l1->next;
            l1->next=NULL;
        }
    	return head;
    }
};