Stack and Queue

Stack

typedef struct{
    int *elem;
    int length;
    int alloc_length;
}stack;
void stack_init(stack &s){
    s.length = 0;
    s.alloc_length = 4;
    s.elem = new int[s.alloc_length]; 
    assert(s.elem != nullptr);
}
void stack_dispose(stack &s){
    delete[] s.elem;
}
void stack_push(stack &s,int key){
    if(s.length == s.alloc_length){
        s.alloc_length *= 2;
        int *temp = s.elem;
        s.elem =  new int[s.alloc_length];
        assert(s.elem != nullptr);
        for(int i=0;i<s.length;i++){
            s.elem[i] = temp[i];
        }
        delete[] temp;
    }
    s.elem[s.length++] = key;
}
int stack_pop(stack &s){
    assert(s.length > 0);
    s.length--;
    return s.elem[s.length];
}

Queue

typedef struct{
    int *elem;
    int size;
    int alloc_length;
}Queue;
void queue_init(Queue &s){
    s.size = 0;
    s.alloc_length = 4;
    s.elem = new int[s.alloc_length];
}
void queue_dispose(Queue &s){
    delete[] s.elem;
}
void queue_push(Queue &s, int key){
    if(s.size == s.alloc_length){
        s.alloc_length *= 2;
        int *t = s.elem;
        s.elem = new int[s.alloc_length];
        for(int i=0; i<s.size; i++){
            s.elem[i] = t[i];
        }
        delete[] t;
    }
    s.elem[s.size++] = key;
}
int queue_pop(Queue &s){
    assert(s.size > 0);
    int key = s.elem[0];
    //s.elem = s.elem + 1; 
    //can't do this way,if so,original s.elem will be lost,then we can't use delete[] s.elem in queue_dispose
    for(int i=0; i<s.size; i++){
        s.elem[i] = s.elem[i+1];//when i=s.size-1,the last element will be ereased
    }
    s.size--;
    return key;
}

重复项和索引项

禁止重复项：

• 旧项遗忘
• 新项忽略

特例：栈的元素为整数。

typedef struct{
    int *elem;//store elements
    int *index;//tell if a certain element in stack
    int size;
    int alloc_size;
}Stack;
//新项忽略,easy
void stack_push(Stack &s, int key){
    if(s.elem[key] == 1){
        return;
    }
    s.elem[s.size++] = key;
    s.index[key] = 1;
}
//旧项遗忘
void stack_push(Stack &s, int key){
    if(s.elem[key] == 1){
        look_delete(s,key);
        s.elem[s.size] = key;
    }
    s.elem[s.size++] = key;
    s.index[key] = 1;
}