为区分队空队满有3种处理方式：
①牺牲一个单元
②增设表示元素个数的数据成员
③增设tag数据成员

1.front->队头元素，rear->队尾元素下一位置

1.1牺牲一个单元

1.1.1定义

#define MaxSize 50
typedef struct {ElemType data[MaxSize];int front, rear;
}SqQueue;

1.1.2初始化

void InitQueue(SqQueue &Q) {Q.rear = Q.front = 0;
}

1.1.3判空

bool isEmpty(SqQueue Q) {if(Q.rear = Q.front)return true;elsereturn false;
}

1.1.4 入队

bool EnQueue(SqQueue &Q, ElemType x) {if((Q.rear + 1) % MaxSize == Q.front)//队满报错return false;Q.data[Q.rear] = x;Q.rear = (Q.rear + 1) % MaxSize;return true;
}

1.1.5出队

bool DeQueue(SqQueue &Q, ElemType &x) {if(Q.rear = Q.front)//队空报错return false;x = Q.data[Q.front];Q.front= (Q.front+ 1) % MaxSize;return true;
}

1.1.6 读队头元素

bool GetHead(SqQueue &S, ElemType &x) {if(Q.rear = Q.front)//队空报错return false;x = Q.data[Q.front];return true;
}

1.2增设表示元素个数的数据成员

1.2.1定义

#define MaxSize 50
typedef struct {ElemType data[MaxSize];int front, rear;int size;
}SqQueue;

1.2.2初始化

void InitQueue(SqQueue &Q) {Q.rear = Q.front = 0;Q.size = 0;
}

1.2.3判空

bool isEmpty(SqQueue Q) {if(Q.size == 0)return true;elsereturn false;
}

1.2.4 入队

bool EnQueue(SqQueue &Q, ElemType x) {if(Q.size == MaxSize)//队满报错return false;Q.data[Q.rear] = x;Q.rear = (Q.rear + 1) % MaxSize;return true;
}

1.2.5出队

bool DeQueue(SqQueue &Q, ElemType &x) {if(Q.size == 0)//队空报错return false;x = Q.data[Q.front];Q.front= (Q.front+ 1) % MaxSize;return true;
}

1.2.6 读队头元素

bool GetHead(SqQueue &S, ElemType &x) {if(Q.size == 0)//队空报错return false;x = Q.data[Q.front];return true;
}

1.3增设tag数据成员

1.3.1定义

#define MaxSize 50
typedef struct {ElemType data[MaxSize];int front, rear;int tag;
}SqQueue;

1.3.2初始化

void InitQueue(SqQueue &Q) {Q.rear = Q.front = 0;Q.tag = 0;
}

1.3.3判空

bool isEmpty(SqQueue Q) {if(Q.rear = Q.front && Q.tag == 0)return true;elsereturn false;
}

1.3.4 入队

bool EnQueue(SqQueue &Q, ElemType x) {if(Q.rear = Q.front && Q.tag == 1)//队满报错return false;Q.data[Q.rear] = x;Q.rear = (Q.rear + 1) % MaxSize;tag = 1;return true;
}

1.3.5出队

bool DeQueue(SqQueue &Q, ElemType &x) {if(Q.rear = Q.front && Q.tag == 0)//队空报错return false;x = Q.data[Q.front];Q.front= (Q.front+ 1) % MaxSize;tag = 1;return true;
}

1.2.6 读队头元素

bool GetHead(SqQueue &S, ElemType &x) {if(Q.rear = Q.front && Q.tag == 0)//队空报错return false;x = Q.data[Q.front];return true;
}

2.front->队头元素，rear->队尾元素

2.1牺牲一个单元

2.1.1定义

#define MaxSize 50
typedef struct {ElemType data[MaxSize];int front, rear;
}SqQueue;

2.1.2初始化

void InitQueue(SqQueue &Q) {Q.front = 0;Q.rear = MaxSize - 1;
}

2.1.3判空

bool isEmpty(SqQueue Q) {if((Q.rear + 1) % MaxSize == Q.front)return true;elsereturn false;
}

2.1.4 入队

bool EnQueue(SqQueue &Q, ElemType x) {if((Q.rear + 2) % MaxSize == Q.front)//队满报错return false;Q.rear = (Q.rear + 1) % MaxSize;Q.data[Q.rear] = x;return true;
}

2.1.5出队

bool DeQueue(SqQueue &Q, ElemType &x) {if((Q.rear + 1) % MaxSize == Q.front)//队空报错return false;x = Q.data[Q.front];Q.front= (Q.front+ 1) % MaxSize;return true;
}

2.1.6 读队头元素

bool GetHead(SqQueue &S, ElemType &x) {if((Q.rear + 1) % MaxSize == Q.front)//队空报错return false;x = Q.data[Q.front];return true;
}

2.2增设表示元素个数的数据成员

2.2.1定义

#define MaxSize 50
typedef struct {ElemType data[MaxSize];int front, rear;int size;
}SqQueue;

2.2.2初始化

void InitQueue(SqQueue &Q) {Q.front = 0;Q.rear = MaxSize - 1;Q.size = 0;
}

2.2.3判空

bool isEmpty(SqQueue Q) {if(Q.size == 0)return true;elsereturn false;
}

2.2.4 入队

bool EnQueue(SqQueue &Q, ElemType x) {if(Q.size == MaxSize)//队满报错return false;Q.rear = (Q.rear + 1) % MaxSize;Q.data[Q.rear] = x;return true;
}

2.2.5出队

bool DeQueue(SqQueue &Q, ElemType &x) {if(Q.size == 0)//队空报错return false;x = Q.data[Q.front];Q.front= (Q.front+ 1) % MaxSize;return true;
}

2.2.6 读队头元素

bool GetHead(SqQueue &S, ElemType &x) {if(Q.size == 0)//队空报错return false;x = Q.data[Q.front];return true;
}

2.3增设tag数据成员

2.3.1定义

#define MaxSize 50
typedef struct {ElemType data[MaxSize];int front, rear;int tag;
}SqQueue;

2.3.2初始化

void InitQueue(SqQueue &Q) {Q.front = 0;Q.rear = MaxSize - 1;Q.tag = 0;
}

2.3.3判空

bool isEmpty(SqQueue Q) {if((Q.rear + 1) % MaxSize == Q.front && Q.tag == 0)return true;elsereturn false;
}

2.3.4 入队

bool EnQueue(SqQueue &Q, ElemType x) {if((Q.rear + 1) % MaxSize == Q.front && Q.tag == 1)//队满报错return false;Q.rear = (Q.rear + 1) % MaxSize;Q.data[Q.rear] = x;tag = 1;return true;
}

2.3.5出队

bool DeQueue(SqQueue &Q, ElemType &x) {if((Q.rear + 1) % MaxSize == Q.front && Q.tag == 0)//队空报错return false;x = Q.data[Q.front];Q.front= (Q.front+ 1) % MaxSize;tag = 1;return true;
}

2.3.6 读队头元素

bool GetHead(SqQueue &S, ElemType &x) {if((Q.rear + 1) % MaxSize == Q.front && Q.tag == 0)//队空报错return false;x = Q.data[Q.front];return true;
}