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

struct LinkNode
{
    int Val;
    struct LinkNode *Next;
};

static int count;

void addEnd(struct LinkNode *root,int val);
void removeEnd(struct LinkNode *root);
struct LinkNode* reverse(struct LinkNode *root);
void display(struct LinkNode *root);

/*
output:
0 -> 1 -> 2 -> 3
3 -> 2 -> 1 -> 0
3 -> 2 -> 1
*/
int main(void)
{
    struct LinkNode *root = (struct LinkNode*)malloc(sizeof(struct LinkNode));
    count = 0;

    root->Val = 0;
    addEnd(root,1);
    addEnd(root,2);
    addEnd(root,3);
    display(root);

    root = reverse(root);
    display(root);

    removeEnd(root);
    display(root);

    getchar();
}

void addEnd(struct LinkNode *root,int val)
{
    struct LinkNode *cur,*newNode;

    cur = root;
    newNode = (struct LinkNode*)malloc(sizeof(struct LinkNode));

    newNode->Val = val;
    for(size_t i = 0; i < count; i++)
    {
        cur = cur->Next;
    }
    cur->Next = newNode;
    count++;
}

void removeEnd(struct LinkNode *root)
{
    struct LinkNode *cur;
    cur = root;

    for(size_t i = 0; i < count; i++)
    {
        cur = cur->Next;
    }
    count--;
    free(cur);
}

struct LinkNode* reverse(struct LinkNode *root)
{
    struct LinkNode *prev,*cur,*next;

    cur = root;

    for(size_t i = 0; i < count + 1; i++)
    {
        next = cur->Next;
        cur->Next = prev;
        prev = cur;
        cur = next;
    }

    return prev;
}

void display(struct LinkNode *root)
{
    struct LinkNode *cur;

    cur = root;

    for(size_t i = 0; i < count + 1; i++)
    {
        if (i == count) {
            printf("%d\n",cur->Val);
        } else
        {
            printf("%d -> ",cur->Val);
        }

        cur = cur->Next;
    }
}