带头节点的单链表

单链表特点：逻辑上相邻，物理上不一定相邻

头插o(1) 随机插入以及尾插 o(n)

头删o(1) 按位置按值删除或尾删 o(n)

查找 o(n)

结构体设计：

typedef struct Node {
	int data;
	Node* next;
}Node,*PNode;

初始化函数：

PNode Init_list(PNode head) {
	Node* s = （Node*)malloc(sizeof(Node));
    assert(s!=NULL);
	s->next = NULL; 
	return s;
}

头插：

bool Insert_Head(PNode plist, int val) {
	assert(plist != NULL);
	PNode s = (PNode)malloc(sizeof(Node));  //1
	assert(s != NULL);
	s->data = val;
                                            //2
	s->next = plist->next;                  //3
	plist->next = s;
	return true;
}

尾插：

bool Insert_Tail(PNode plist, int val) {
	assert(plist != NULL);
	PNode s = （Node*)malloc(sizeof(Node));
    assert(s!=NULL);
	//PNode pr = plist;
	//PNode p = plist->next;
	//while (p != NULL) {
	//	p = p->next;
	//	pr = pr->next;
	//}
	//pr->next = s;
	PNode p = plist;
	for (; p->next != NULL; p = p->next) {

	}
	p->next = s;
	s->next = NULL;
	return true;
}

按位置插

bool Insert_Pos(PNode plist, int pos, int val) {
	assert(plist != NULL && pos >= 0 && pos <= Get_Length(plist));
	PNode s = (Node*)malloc(sizeof(Node));
    assert(s!=NULL);
    s->data=val;
	PNode p = plist;
	for (int i = 0; i < pos; i++) {
		p = p->next;
	}
	s->next = p->next;
	p->next = s;
	return true;
}

查找： 在plist指向的单链表中值为val的第一个节点 找到后返回其地址，否则返回NULL

PNode Search(PNode plist, int val) {
	assert(plist != NULL);
	PNode p = plist->next;
	while (p->data != val) {
		p = p->next;
	}
	return p;
}

头删

bool Del_Head(PNode plist) {

	PNode p = plist->next;
	plist->next = p->next;
	free(p);
	p = NULL;
	return true;
}

尾删

bool Del_Tail(PNode plist) {
	PNode p = plist;
	for (; p->next != NULL; p = p->next) {
		if (p->next->next == NULL) {
			break;
		}
	}
	PNode q = p->next;
	p->next = q->next;
	free(q);
	q = NULL;
	return true;
}

按位置删

bool Del_Pos(PNode plist, int pos) {
	//assert()
	PNode pr = plist;
	PNode p = plist->next;
	for (int i = 0; i < pos; i++) {
		pr = pr->next;
		p = p->next;
	}
	pr->next = p->next;
	free(p);
	p = NULL;
	return true;
}

按值删

bool Del_Val(PNode plist, int val) {
	assert(plist != NULL);
	PNode p = GetPrior(plist, val);
	if (p == NULL) {
		return false;
	}
	PNode q = p->next;
	p->next = q->next;
	free(q);
	q = NULL;
	return true;
	//PNode pr = plist;
	//PNode p = plist->next;
	//while (p->data != val) {
	//	pr = pr->next;
	//	p = p->next;
	//}
	//pr->next = p->next;
	//free(p);
	//p = NULL;
	//return true;

}

判空

bool IsEmpty(PNode plist) {
	return plist->next == NULL;
}

获取前驱(将值为val的节点的前一个节点返回)

PNode GetPrior(PNode plist, int val) {
	PNode p = plist;
	for (; p->next != NULL; p = p->next) {
		if (val == p->next->data) {
			return p;
		}
	}
	return NULL;
}

获取后继

PNode Get_Next(PNode plist, int val) {
	PNode p = Search(plist, val);
	return p->next;
}

获取有效节点个数

int Get_Length(PNode plist) {
	assert(plist != NULL);
	int i = 0;
	for (PNode p = plist->next; p != NULL; p = p->next) {
		//printf("%d ", p->data);

		i++;
	}
	return i;
}

打印函数

void Print(PNode plist) {
	assert(plist != NULL);
	PNode p = plist->next;
	while (p != NULL) {
		printf("%d ", p->data);
		p = p->next;
	}
	printf("\n");
}

标签：单链,带头,val,NULL,节点,PNode,return,next,plist
来源： https://blog.csdn.net/weixin_50626842/article/details/120771929