两个链表有序 合并成一个链表

1、递归实现

Node * Merge(Node *head1 , Node *head2){if ( head1 == NULL )return head2 ;if ( head2 == NULL)return head1 ;Node *head = NULL ;if ( head1->data < head2->data ){head = head1 ;head->next = Merge(head1->next,head2);}else{head = head2 ;head->next = Merge(head1,head2->next);}return head ;}

2、非递归实现

Node * Merge(Node *head1 , Node *head2){if ( head1 == NULL)return head2 ;if ( head2 == NULL)return head1 ;Node *head = NULL ;Node *p1 = NULL;Node *p2 = NULL;if ( head1->data < head2->data ){head = head1 ;p1 = head1->next;p2 = head2 ;}else{head = head2 ;p2 = head2->next ;p1 = head1 ;}Node *pcurrent = head ;while ( p1 != NULL && p2 != NULL){if ( p1->data <= p2->data ){pcurrent->next = p1 ;pcurrent = p1 ;p1 = p1->next ;}else{pcurrent->next = p2 ;pcurrent = p2 ;p2 = p2->next ;}}if ( p1 != NULL )pcurrent->next = p1 ;if ( p2 != NULL )pcurrent->next = p2 ;return head ;}