【数据结构】09 线性表的链式存储实现

定义

线性表的链式存储不需要用连续的存储单元来实现，不需要逻辑上相邻的两个数据元素在物理上也相邻，它是通过链建立其数据元素之间的逻辑关系，因此对线性表的插入、删除不需要移动数据元素，只需要修改连。

为了访问链表，必须找到链表的第一个数据单元，因此实际应用中常用一个称为“表头(Header)”的指针指向链表的第一个单元，并用它表示一个具体的链表。

结点的结构定义

typedef int ElementType;
typedef struct LNode* PtrToLNode;
typedef PtrToLNode Position;
typedef PtrToLNode List;

struct LNode {
	ElementType Data;
	PtrToLNode Next;
};

相关操作

初始化

List MakeEmpty(List L) {
	L = (LNode*)malloc(sizeof(LNode));
	L->Next = NULL;
	return L;
}

插入

bool Insert(List L, ElementType X, int i) {
	int cnt = 0;
	List p = L;
	//printf("p: %d\n", p->Data);
	while (p != NULL && cnt != i-1) {
		p = p->Next;
		cnt++;
	}
	//printf("cnt: %d\n", cnt);
	if (p == NULL || cnt != i - 1) {
		printf("insert error!\n");
		return false;
	}
	else {
		List temp = (LNode*)malloc(sizeof(LNode) * 1);
		temp->Data = X;
		
		temp->Next = p->Next;
		p->Next = temp;
	}
	return true;

}

求表长

int ListLength(List L) {
	int length = 0;
	List p = L->Next;
	while (p != NULL) {
		p = p->Next;
		length++;
	}
	return length;

}

查找

按序号查找

ElementType Findkth(List L, int K) {
	//找到第i个结点的值
	List p = L->Next;
	int i = 1;
	while (p != NULL && i != K) {
		p = p->Next;
		i++;
	}

	if (p == NULL || i != K) {
		printf("can't find!\n");
		return -1;
	}
	else {
		return p->Data;
	}
	
}

按值查找

Position Find(List L, ElementType X) {
	//由数值返回其结点位置
	List p = L->Next;
	while (p != NULL && p->Data !=X) {
	
		p = p->Next;
	}

	if (p->Data == X) {
		return p;
	}
	else{
		return NULL;
	}

}

删除

bool Deletei(List L, int i) {
	//删除第i个结点
	List p=L, q = L;
	int cnt = 0;
	while (p != NULL && cnt!=i) {
		cnt++;
		q = p;
		p = p->Next;
	}
	if (p == NULL || cnt != i) {
		return false;
	}
	q->Next = p->Next;
	free(p);
	return true;

}

完整代码

# include <stdio.h>
# include <stdlib.h>

typedef int ElementType;
typedef struct LNode* PtrToLNode;
typedef PtrToLNode Position;
typedef PtrToLNode List;

struct LNode {
	ElementType Data;
	PtrToLNode Next;
};

List MakeEmpty(List L) {
	L = (LNode*)malloc(sizeof(LNode));
	L->Next = NULL;
	return L;
}

bool Insert(List L, ElementType X, int i) {
	int cnt = 0;
	List p = L;
	//printf("p: %d\n", p->Data);
	while (p != NULL && cnt != i-1) {
		p = p->Next;
		cnt++;
	}
	//printf("cnt: %d\n", cnt);
	if (p == NULL || cnt != i - 1) {
		printf("insert error!\n");
		return false;
	}
	else {
		List temp = (LNode*)malloc(sizeof(LNode) * 1);
		temp->Data = X;
		
		temp->Next = p->Next;
		p->Next = temp;
	}
	return true;

}
void print_link(List L) {
	List p = L->Next;
	while (p != NULL) {
		printf("Node : %d\n", p->Data);
		p = p->Next;
		
	}
	
}

int ListLength(List L) {
	int length = 0;
	List p = L->Next;
	while (p != NULL) {
		p = p->Next;
		length++;
	}
	return length;

}

ElementType Findkth(List L, int K) {
	//找到第i个结点的值
	List p = L->Next;
	int i = 1;
	while (p != NULL && i != K) {
		p = p->Next;
		i++;
	}

	if (p == NULL || i != K) {
		printf("can't find!\n");
		return -1;
	}
	else {
		return p->Data;
	}
	
}

Position Find(List L, ElementType X) {
	//由数值返回其结点位置
	List p = L->Next;
	while (p != NULL && p->Data !=X) {
	
		p = p->Next;
	}

	if (p->Data == X) {
		return p;
	}
	else{
		return NULL;
	}

}

bool Deletei(List L, int i) {
	//删除第i个结点
	List p=L, q = L;
	int cnt = 0;
	while (p != NULL && cnt!=i) {
		cnt++;
		q = p;
		p = p->Next;
	}
	if (p == NULL || cnt != i) {
		return false;
	}
	q->Next = p->Next;
	free(p);
	return true;

}


int main() {
	List L = NULL;
	L  = MakeEmpty(L);
	printf("Finish init!\n");
	ElementType X;
	int N;
	scanf_s("%d", &N);
	while (N--) {
		scanf_s("%d", &X);
		if (Insert(L, X, 1) == false) {
			printf("insert error!\n");
		}
		
	}
	print_link(L);
	int length = ListLength(L);
	printf("the list's length: %d\n", length);

	/*int x = Findkth(L, 2);
	printf("find: %d\n", x);

	List p = Find(L, 5);
	printf("findp: p->data: %d\n", p->Data);*/

	if (bool(Deletei(L, 2))) {
		printf("Delete Sucessfully!\n");
	}


	print_link(L);
	length = ListLength(L);
	printf("the list's length: %d\n", length);
	
}