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DSBookCode/BookCode/第3章/3.11-3.15/3.11-3.15.cpp

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+/***循环队列基本操作***/
+
+#include<iostream>
+#include<fstream>
+using namespace std;
+
+#define MAXQSIZE 100
+#define OK 1
+#define ERROR 0
+#define OVERFLOW -2
+typedef char QElemType;
+typedef char SElemType;
+typedef int Status;
+
+typedef struct {
+	QElemType *base;//初始化时动态分配存储空间
+	int front;//头指针
+	int rear;//尾指针
+} SqQueue;
+
+//算法3.11　循环队列的初始化
+Status InitQueue(SqQueue &Q) {//构造一个空队列Q
+	Q.base = new QElemType[MAXQSIZE]; //为队列分配一个最大容量为MAXSIZE的数组空间
+	if (!Q.base)
+		exit(OVERFLOW); //存储分配失败
+	Q.front = Q.rear = 0; //头指针和尾指针置为零，队列为空
+	return OK;
+}
+
+//算法3.12　求循环队列的长度
+int QueueLength(SqQueue Q) {//返回Q的元素个数，即队列的长度
+	return (Q.rear - Q.front + MAXQSIZE) % MAXQSIZE;
+}
+
+//算法3.13　循环队列的入队
+Status EnQueue(SqQueue &Q, QElemType e) {//插入元素e为Q的新的队尾元素
+	if ((Q.rear + 1) % MAXQSIZE == Q.front) //尾指针在循环意义上加1后等于头指针，表明队满
+		return ERROR;
+	Q.base[Q.rear] = e; //新元素插入队尾
+	Q.rear = (Q.rear + 1) % MAXQSIZE; //队尾指针加1
+	return OK;
+}
+
+//算法3.14　循环队列的出队
+Status DeQueue(SqQueue &Q, QElemType &e) {//删除Q的队头元素，用e返回其值
+	if (Q.front == Q.rear)
+		return ERROR; //队空
+	e = Q.base[Q.front]; //保存队头元素
+	Q.front = (Q.front + 1) % MAXQSIZE; //队头指针加1
+	return OK;
+}
+
+//算法3.15　取循环队列的队头元素
+SElemType GetHead(SqQueue Q) {//返回Q的队头元素，不修改队头指针
+	if (Q.front != Q.rear) //队列非空
+		return Q.base[Q.front]; //返回队头元素的值，队头指针不变
+}
+
+int main() {
+	int choose, flag = 0;
+	SqQueue Q;
+	QElemType e, j;
+	cout << "1.初始化\n";
+	cout << "2.入队\n";
+	cout << "3.读队头元素\n";
+	cout << "4.出队\n";
+	cout << "0.退出\n\n";
+
+	choose = -1;
+	while (choose != 0) {
+		cout << "请选择:";
+		cin >> choose;
+		switch (choose) {
+		case 1://算法3.16　链队的初始化
+			if (InitQueue(Q)) {
+				flag = 1;
+				cout << "成功对队列进行初始化\n\n";
+			} else
+				cout << "初始化队列失败\n\n";
+			break;
+		case 2: {//算法3.17　链队的入队
+			fstream file;
+			file.open("QNode.txt");
+			if (!file) {
+				cout << "错误！未找到文件！\n\n" << endl;
+				exit(ERROR);
+			}
+			if (flag) {
+				flag = 1;
+				cout << "入队的元素依次为：\n";
+				while (!file.eof()) {
+					file >> j;
+					if (file.fail())
+						break;
+					else {
+						EnQueue(Q, j);
+						cout << j << "  ";
+					}
+				}
+				cout << endl << endl;
+			} else
+				cout << "队列未建立，请重新选择\n\n";
+			file.close();
+		}
+			break;
+		case 3://算法3.19　取链队的队头元素
+			if (flag != -1 && flag != 0)
+				cout << "队头元素为：\n" << GetHead(Q) << endl << endl;
+			else
+				cout << "队列中无元素，请重新选择\n" << endl;
+			break;
+		case 4://算法3.18　链队的出队
+			cout << "依次弹出的队头元素为:\n";
+			while (DeQueue(Q, e)) {
+				flag = -1;
+				cout << e << "  ";
+			}
+			cout << endl << endl;
+			break;
+		}
+	}
+	return 0;
+}