一日一码07——链表

/*带头结点链表常用操作*/

#include <stdio.h>

typedef struct Node
{
	int data;
	struct Node *next;   //漏写过struct
} Node;

Node* createList(int *arr, int n);

int insertList(Node* head, int pos, int data);

int deleteList(Node* head, int pos);

void reverseList(Node **head);

void printList(Node* head);

Node* createList(int* arr, int n){
	Node *head = NULL;
	Node *p,*q;
	int i = 0;

	head = (Node*)malloc(sizeof(Node));
	p = head;

	for (i = 0; i < n; ++i)
	{
		q = (Node*)malloc(sizeof(Node));
		q->data = arr[i];
		p->next = q;
		p = q;
	}

	p->next = NULL;

	return head;
}

int insertList(Node* head, int pos, int data){
	int i = 0;
	Node *p,*q;
	p = head;
	while( p->next != NULL && ++i < pos){
		p = p->next;
	}

	if ( i != pos)
	{
		printf("Insert fail,the postion is not exist.\n");
		return -1;
	}

	q = (Node*)malloc(sizeof(Node));
	q->data = data;
	q->next = p->next;
	p->next = q;
	return 0;
}

int deleteList(Node* head, int pos){
	int i = 0;
	Node *p,*q;
	p = head;
	while( p->next != NULL && ++i < pos){
		p = p->next;
	}

	if ( i != pos)
	{
		printf("delete fail,the postion is not exist.\n");
		return -1;
	}
	q = p->next;
	p->next = q->next;
	free(q);

	return 0;
}

void reverseList(Node **head){
	Node *p,*q,*e;
	e = NULL;
	p = (*head)->next;
	
	if (p == NULL)
	{
		return;
	}

	while(p->next != NULL){
		q = p;
		p = p->next;
		q->next = e;
		e = q;
	}
	p->next = e;
	(*head)->next = p;
}

void printList(Node* head){
	Node* p;
	p = head;

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

int main(int argc, char const *argv[])
{
	int arr[5] = {1,2,3,4,5};
	Node* head;

	head = createList(arr,5);
	printList(head);
	reverseList(&head);
	printList(head);

	return 0;
}