leetcode Merge Two Sorted Lists
/** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next; * ListNode(int x) : val(x), next(NULL) {} * }; */ class Solution { public: ListNode *mergeTwoLists(ListNode *l1, ListNode *l2) { ListNode *head; ListNode *p=l1,*q=l2; if(p==NULL)return q; if(q==NULL)return p; if(p->val<q->val) { head=p; p=p->next; } else { head=q; q=q->next; } ListNode *r=head; while(p&&q) { if(p->val<q->val) { r->next=p; p=p->next; } else { r->next=q; q=q->next; } r=r->next; } if(p==NULL) { r->next=q; } if(q==NULL) { r->next=p; } return head; } };
题目很容易,但是要写出没有bug的代码却不容易。