数据结构之队列——回文字判断

题目：判别回文字符串

正读和反读都一样的字符串称为回文字符串。
编写程序，在键盘上输入一个字符串，以“#”作为结束标志，判别它是否为回文字符串。要求：采用栈和队列来实现

#include <stdio.h>
#include <stdlib.h>
#define ERROR 0
#define OK 1

typedef struct node{
	char data;
	struct node *next;
}queue,stack,*LinkQueue,*LinkStack;

int push(LinkStack &sHead, char ch){//入栈操作
	LinkStack p = (LinkStack)calloc(1, sizeof(stack));
	if (p == NULL){
		printf("Error calloc.\n");
		return ERROR;
	}
	p->data = ch;
	p->next = sHead;
	sHead = p;
	return OK;
}

char pop(LinkStack &sHead){//出栈
	if (NULL == sHead) return ERROR;
	LinkStack temp = sHead;
	char ch = sHead->data;
	sHead = sHead->next;
	free(temp);
	return ch;
}

int enqueue(LinkQueue &qHead, LinkQueue &qRear, char ch){//进入队列操作
	LinkQueue p = (LinkQueue)calloc(1, sizeof(queue));//动态分配空间并初始化
	if (p == NULL){
		printf("Error calloc_queue.\n");
		return ERROR;
	}
	p->data = ch;
	p->next = NULL;
	if (NULL != qRear)
		qRear->next = p;
	if (NULL == qHead)
		qHead = qRear;
	qRear = p;
	return OK;
}

int queueDel(LinkQueue &qHead){//进行队列删除
	if (qHead == NULL) return OK;
	LinkQueue temp = qHead;
	qHead = qHead->next;
	free(temp);
	return OK;
}

char dequeue(LinkQueue &qHead){//进行出队列操作
	char ch = qHead->data;
	LinkQueue temp = qHead;
	qHead = qHead->next;
	queueDel(temp);
	return ch;
}

void input(LinkStack &sHead, LinkQueue &qHead,LinkQueue &qRear,int &len){
	char ch;
	printf("Please input the string which would be judged:");
	while (scanf("%c", &ch) && '#' != ch){
		push(sHead, ch);//推入栈
		enqueue(qHead ,qRear, ch);//进入队列
		len++;
	}
}

int compare(LinkStack &sHead, LinkQueue &qHead,int len){
    int cnt = 0;
	while (sHead != NULL && qHead != NULL && cnt <= len/2){//判断一半的栈和队列是否已空
		if (pop(sHead) != dequeue(qHead))//比较对应字符是否相同
			return ERROR;//不同直接退出比较
        cnt++;
	}
	return OK;//始终相同，匹配
}

void output(LinkStack &sHead, LinkQueue &qHead,int len){
	if (compare(sHead, qHead,len))//调用判断函数进行判断是否满足
		printf("It is a plalindrome.\n");
	else printf("It isn't a plalindrome.\n");
}

int main(){
    //freopen("input.txt","r",stdin);
    //freopen("output.txt","w",stdout);
    int len=0;
	LinkStack sHead = NULL;//栈的头结点指针
	LinkQueue qHead = NULL ,qRear = NULL;//队列的头结点和尾节点指针
	input(sHead, qHead,qRear,len);
	output(sHead, qHead,len);
	return 0;
}