两数相加模板:
//n进制数相加
int carry=0;
int bit;
int 数1,数2;
point1指向数1的最低位,point2指向数2的最低位
res;//结果
while(point1不到最高位&&point2不到最高位)
{
bit=point1->val +point2->val+carry;
if(bit>=n)
{
carry=1;
结果最后加入数(bit-n);
}
else
{
carry=0;
结果最后加入数(bit);
}
}
while(point1不到最高位)
{
bit= point1->val+carry;
if(bit>=n)
{
carry=1;
结果加入数(bit-n);
}
else{
carry=0;
结果加入数(bit);
}
}
while(point2不到最高位)
{
bit=point2->val+carry;
if(bit>=n)
{
carry=1;
结果加入数(bit-10);
}
else{
carry=0;
结果加入数(bit);
}
}
//如果到最后还有进位没加
if(carry==1)
{
结果加入数(1);
}
return 结果;
}
};
具体思路:
(1)用存放节点类型的栈来实现从低位向高位的遍历
(2)用头插法实现向结果串中添加位数
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode() : val(0), next(nullptr) {}
* ListNode(int x) : val(x), next(nullptr) {}
* ListNode(int x, ListNode *next) : val(x), next(next) {}
* };
*/
class Solution {
public:
ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
stack<ListNode*>st1;
stack<ListNode*>st2;
ListNode *head=new ListNode();
ListNode *p=l1;
while(p)
{
st1.push(p);
p=p->next;
}
p=l2;
while(p)
{
st2.push(p);
p=p->next;
}
ListNode *p1,*p2,*s;
int carry=0;
int bit;
while(!st1.empty()&&!st2.empty())
{
p1=st1.top();
st1.pop();
p2=st2.top();
st2.pop();
bit=p1->val+p2->val+carry;
if(bit>=10)
{
carry=1;
s=new ListNode(bit-10);
s->next=head->next;
head->next=s;
}
else
{
carry=0;
s=new ListNode(bit);
s->next=head->next;
head->next=s;
}
}
while(!st1.empty())
{
p1=st1.top();
st1.pop();
bit=p1->val+carry;
if(bit>=10)
{
carry=1;
s=new ListNode(bit-10);
s->next=head->next;
head->next=s;
}
else{
carry=0;
s=new ListNode(bit);
s->next=head->next;
head->next=s;
}
}
while(!st2.empty())
{
p2=st2.top();
st2.pop();
bit=p2->val+carry;
if(bit>=10)
{
carry=1;
s=new ListNode(bit-10);
s->next=head->next;
head->next=s;
}
else{
carry=0;
s=new ListNode(bit);
s->next=head->next;
head->next=s;
}
}
if(carry==1)
{
s=new ListNode(1);
s->next=head->next;
head->next=s;
}
return head->next;
}
};