单链表的插入与删除

单链表的插入与删除

ListInsert(&L,i,e) 插入操作。在表L中的第i个位置上插入指定元素e

按位序插入(带头结点)

typedef struct LNode{ElemType data;struct LNode *next;
}LNode,*LinkList;
bool ListInsert(LinkList &L,int i,ElemType e){if(i<1){return false;}LNode *p;int j = 0;p = L;while(p!=NULL && j < i-1){p=p->next;j++;}if(p == NULL){return false;}LNode *s = (LNode *)malloc(sizeof(LNode));s->data = e;s->next = p->next;p->next = s;return true;
}
平均时间复杂度 T(n) = O(n)

按位序插入(不带头结点)

bool ListInsert(LinkList &L,int i,ElemType e){if(i<1){return false;}if(i == 1){LNode *s = (LNode *)malloc(sizeof(LNode));s ->data = e;s->next = L;L=s;return true;}LNode *p;int j =1;p = L;while(p != NULL && j < i-1){p=p->next;j++;}LNode *s = (LNode *)malloc(sizeof(LNode));s.data = e;s.next = p.next;p.next = s;return true;
}

指定结点的后插操作

//在p结点之后插入元素e
bool InsertNextNode(LNode *p,ElemType e){if(p == NULL){return false;}LNode *s = (LNode *)malloc(sizeof(LNode));if(s == NULL){return false;}s->data = e;s->next = p ->next;p->next = s;return true;
}

指定节点的前插操作

bool InsertPrioNode(LinkList &L,LNode *p,ElemType e) 在p结点之前插入元素e

方法一：遍历链表，找到p的前驱q，然后对q进行后插操作

bool InsertPrioNode(LinkList &L,LNode *p,ElemType e){if(p == NULL){return false;}LNode *q=(LNode *)malloc(sizeof(LNode));q = L;while(q!=NULL && q->next = p){q = q->next;}if(q == NULL){return false;}LNode *s =(LNode *)malloc(sizeof(LNode));s->data = e;s->next = q->next;q->next = s;return true;
}

方法二：在p结点之后插入一个结点s，将p存放的数据赋予s,将元素e赋予p

bool InsertPriorNode(LNode *p,ElemType e){if(p == NULL){return false;}LNode *s = (LNode *)malloc(sizeof(LNode));if(s == NULL){return false;}s->next = p->next;p->next = s;s->data = p->data;p->data =e;return true;
}
时间复杂度O(1)

//前插操作 在p结点之前插入结点s
bool InsertPriorNode(LNode *p,LNode *s){if(p == NULL||s == NULL){return false;}//后插操作s->next = p->next;p->next = s;//交换数据域ElemType temp = p->data;p->data = s->data;s->data = temp;return true;
}

按位序删除

ListDelete(LinkList &L,int i,ElemType &e) 删除操作，删除表L中第i个位置的元素，并用e返回删除元素的值。找到i-1个结点

bool ListDelete(LinkList &L,int i,ElemType &e){if(i<1)return false;LNode *p;int j = 0;while(p != NULL && j<i-1){p=p->next;j++;}if(p == NULl){return false;}if(p->next == NULL){return false;}LNode *q = p->next;e = q->data;p->next = q->next;free(q);return true;
}

指定结点的删除

//删除指定结点p
bool DeleteNode(LNode *p){if(p == NULL){return false;}LNode *q = p->next;p->data = q ->data;p->next = q->next;free(q);return true;
}
//如果p是最后一个结点，只能从表头开始依次寻找P的前驱