练习:合并两个排序链表
一、题目要求:
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。
二、代码(2018–7-19)
/*
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;
if(pHead2 == NULL) return pHead1;
ListNode *newHead = NULL, *p1 = pHead1, *p2 = pHead2;
ListNode *p = NULL, *q = NULL;
while(p1 || p2) {
if(p1 && p2 && p1->val >= p2->val) {
q = p2;
p2 = p2->next;
}
else if(p1 && p2 && p1->val < p2->val) {
q = p1;
p1 = p1->next;
}
else if(p1 && (p2 == NULL)) {
q = p1;
p1 = p1->next;
}
else if((p1 == NULL) && p2) {
q = p2;
p2 = p2->next;
}
else {
q = NULL;
break;
}
if(newHead == NULL) {
newHead = q;
p = q;
}
else {
p->next = q;
p = p->next;
}
}
p->next = NULL;
return newHead;
}
};