剑指offer 合并两个排序的链表
- 题目描述
输入两个单调递增的链表，输出两个链表合成后的链表，当然我们需要合成后的链表满足单调不减规则。
- 解法
用归并排序的思想来解决。运行时间：0ms；占用内存：8568k。
/*
struct ListNode {
int val;
struct ListNode *next;
ListNode(int x) :
val(x), next(NULL) {
}
};*/
class Solution {
public:
ListNode* Merge(ListNode* pHead1, ListNode* pHead2)
{
if (pHead1 == NULL)
return pHead2;
else if (pHead2 == NULL)
return pHead1;
ListNode* ret;
if (pHead1->val <= pHead2->val){
ret = pHead1;
pHead1 = pHead1->next;
}
else{
ret = pHead2;
pHead2 = pHead2->next;
}
ListNode* p = ret;
while (pHead1 != NULL && pHead2 != NULL){
if (pHead1->val <= pHead2->val){
p->next = pHead1;
pHead1 = pHead1->next;
}
else{
p->next = pHead2;
pHead2 = pHead2->next;
}
p = p->next;
}
if (pHead1 != NULL)
p->next = pHead1;
else if (pHead2 != NULL)
p->next = pHead2;
return ret;
}
};