记录编号	116761	评测结果	AAAAAAAAAA
题目名称	[USACO Open09] 奶牛队列	最终得分	100
用户昵称	Bokjan	是否通过	通过
代码语言	C++	运行时间	0.080 s
提交时间	2014-08-26 21:29:01	内存使用	0.31 MiB

#include <cstdio>
FILE *fi, *fo;
struct node{
	int data;
	node *prev, *next;
	node(int value)
	{
		data = value;
		prev = next = NULL;
	}
};
class linklist{
public:
	node *head, *tail;
	int size;
	linklist()
	{
		head = tail = NULL;
		size = 0;
	}
	~linklist();
	void AddLeft(int);
	void AddRight(int);
	void DelLeft(int);
	void DelRight(int);
	void Traverse(void);
};
linklist::~linklist()
{
	node *p = head;
	while(NULL != head){
		head = head->next;
		delete p;
		p = head;
	}
}
void linklist::AddLeft(int value)
{
	node *p = new node(value);
	p->next = head;
	if(0 != size)
		head->prev = p;
	head = p;
	if(0 == size)
		tail = head;
	size++;
}
void linklist::AddRight(int value)
{
	node *p = new node(value);
	p->prev = tail;
	if(0 != size)
		tail->next = p;
	tail = p;
	if(0 == size)
		head = tail;
	size++;
}
void linklist::DelLeft(int count)
{
	node *p = head;
	while(count--){
		head = head->next;
		delete p;
		p = head;
	}
	head->prev = NULL;
}
void linklist::DelRight(int count)
{
	node *p = tail;
	while(count--){
		tail = tail->prev;
		delete p;
		p = tail;
	}
	tail->next = NULL;
}
void linklist::Traverse(void)
{
	node *p = head;
	while(p != NULL){
		fprintf(fo, "%d\n", p->data);
		p = p->next;
	}
}
int main(void)
{
	fi = fopen("cline.in", "r");
	fo = fopen("cline.out", "w");
	int s, num = 1;
	linklist cline;
	fscanf(fi, "%d\n", &s);
	while(s--){
		char a, b;
		int k;
		fscanf(fi, "%c %c\n", &a, &b);
		switch(a){
			case 'A':
				switch(b){
					case 'L':
						cline.AddLeft(num);
						break;
					case 'R':
						cline.AddRight(num);
						break;
				}
				num++;
				break;
			case 'D':
				fscanf(fi, "%d\n", &k);
				switch(b){
					case 'L':
						cline.DelLeft(k);
						break;
					case 'R':
						cline.DelRight(k);
						break;
				}
				break;
		}
	}
	cline.Traverse();
	fclose(fi);
	fclose(fo);
	return 0;
}