【链表】非递归过程以O(N)反转单链表

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


struct Node;
typedef Node *PtrToNode;
typedef PtrToNode List;
typedef PtrToNode Position;


struct Node
{
int val;
Position Next;
};


void Insert(int val, List list, Position pos)
{
Node *p;
p = (Node *)malloc(sizeof(Node));
p->val = val;
p->Next=NULL;
pos->Next = p;
}

//数据结构与算法分析 习题3.12
List ReverseList(List L) {
Position CurrentPos, NextPos, PreviousPos;
PreviousPos = NULL;