Add Two Numbers

最新推荐文章于 2021-02-19 08:37:33 发布

yang20141109

最新推荐文章于 2021-02-19 08:37:33 发布

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分类专栏： LeetCode

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本文介绍了一种使用链表数据结构解决两个非负整数相加的问题。通过将整数以逆序方式存储在链表中，实现了两数相加并返回结果链表的功能。文章提供了完整的C++代码实现及示例。

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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#include<iostream>
using namespace std;

//链表数据结构  
struct ListNode
{
	int val;
	ListNode *next;
	ListNode(int x) : val(x), next(NULL) {}
	ListNode(){}
};

//在链表末尾追加元素  
void appendTail(ListNode **pHead, int val)
{
	ListNode *pNew = new ListNode();
	pNew->next = NULL;
	pNew->val = val;

	if (*pHead == NULL)
	{
		*pHead = pNew;
	}
	else
	{
		ListNode *tmp = *pHead;
		while (tmp->next)
		{
			tmp = tmp->next;
		}
		tmp->next = pNew;
	}
}

//正序输出链表  
void show(ListNode *pHead)
{
	while (pHead)
	{
		cout << pHead->val << " ";
		pHead = pHead->next;
	}
	cout << endl;
}

ListNode* addTwoNumbers(ListNode* l1, ListNode* l2)
{
	ListNode *pNewHead = l1;
	bool isFlag = false;//是否产生进位
	//位数相同的相加
	while (l1 != NULL && l2 != NULL)
	{
		int val = 0;
		if (isFlag)
		{
			val = l1->val + l2->val + 1;
		}
		else
		{
			val = l1->val + l2->val;
		}
		if (val >= 10)
		{
			l1->val = val - 10;
			isFlag = true;
		}
		else
		{
			l1->val = val;
			isFlag = false;
		}
		l1 = l1->next;
		l2 = l2->next;
	}

	//如果l1链表的表示的数字大
	while (l1)
	{
		int val = l1->val;
		if (isFlag)
		{
			val = l1->val + 1;
		}
		if (val >= 10)
		{
			l1->val = val - 10;
			isFlag = true;
		}
		else
		{
			l1->val = val;
			isFlag = false;
			break;
		}
		l1 = l1->next;
	}

	ListNode *tmp = l2;
	//如果l2表示的数字大
	while (l2)
	{
		int val = l2->val;
		if (isFlag)
		{
			val = l2->val + 1;
		}
		if (val >= 10)
		{
			l2->val = val - 10;
			isFlag = true;
		}
		else
		{
			isFlag = false;
			break;
		}
		l2 = l2->next;
	}
	ListNode *p = pNewHead;
	while (p->next)
	{
		p = p->next;
	}
	p->next = tmp;
	if (isFlag)
	{
		appendTail(&pNewHead, 1);
	}
	return pNewHead;
}

int main(void)
{
	ListNode *pHead1 = NULL;
	ListNode *pHead2 = NULL;
	appendTail(&pHead1, 9);
	appendTail(&pHead1, 8);
	appendTail(&pHead2, 1);
	ListNode *p1 = addTwoNumbers(pHead1, pHead2);
	show(p1);
	system("pause");
	return 0;
}