c++6级错题

#include <iostream>

using namespace std;

class base {

public:

    virtual void show() {

        cout << "base class" << endl;

    }

};

class derived : public base {

public:

    void show() override {

        cout << "derived class" << endl;

    }

};

int main() {

    base* b;

    derived d;

    b = &d;

    b->show();

    return 0;

}

 1  #include <iostream>

 2  using namespace std;

 3

 4  class MoreData {

 5      int * _data;

 6      int head, tail, capacity;

 7  public:

 8      MoreData(int cap) {

 9          capacity = cap;

10          _data = new int[capacity];

11          head = tail = 0;

12      }

13      MoreData & push(int val) {

14          _data[tail++] = val;

15          return *this;

16      }

17      int pop(){

18          return _data[head++];

19      }

20      int size() {

21          return tail - head;

22      }

23  };

24  int main() {

25      auto myData = MoreData(100);

26      myData.push(1);

27      myData.push(2);

28      myData.push(3);

29      myData.push(11).push(12).push(13);

30      cout << myData.pop() << endl;

31      return 0 ;

32  }

 1  #include <iostream>

 2  using namespace std;

 3

 4  class MoreData {

 5      int * _data;

 6      int head, tail, capacity;

 7  public:

 8      MoreData(int cap) {

 9          capacity = cap;

10          _data = new int[capacity];

11          head = tail = 0;

12      }

13      MoreData & push(int val) {

14          _data[tail++] = val;

15          return *this;

16      }

17      int pop(){

18          return _data[head++];

19      }

20      int size() {

21          return tail - head;

22      }

23  };

24  int main() {

25      auto myData = MoreData(100);

26      myData.push(1);

27      myData.push(2);

28      myData.push(3);

29      myData.push(11).push(12).push(13);

30      cout << myData.pop() << endl;

31      return 0 ;

32  }

 1  #include <iostream>
2 using namespace std;
3
4 class ManyData {
5 int * _data;
6 int head, tail, capacity;
7 public:
8 ManyData(int cap) {
9 capacity = cap;
10 _data = new int[capacity];
11 head = tail = 0;
12 }
13 void push(int val) {
14 _data[tail++] = val;
15 }
16 int pop() {
17 return _data[--tail];
18 }
19 int size() {
20 return tail - head;
21 }
22 };
23 int main() {
24 auto myData = ManyData(100);
25 myData.push(1);
26 myData.push(2);
27 myData.push(3);
28 myData.push(100);
29 cout << myData.size() << endl;
30 cout << myData.pop() << endl;
31 return 0;
32 }

int gcd(int a, int b) {
      while (b != 0) {
      ______________________
      }
     return a;
}

#include <iostream>
using namespace std;
struct TreeNode {

int val;
TreeNode* left;
TreeNode* right;
TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};

TreeNode* search(TreeNode* root, int val) {
cout << root->val << " ";
if (root == NULL || root->val == val) return root;

if (val < root->val)
return search(root->left, val);
else
return search(root->right, val);
}

给定以下二叉搜索树，调用函数 search(root,7) 时，输出的结果是（ ）

    5
    / \
   3 7
  / \ / \
2  4 6  8

struct TreeNode {
int value;
TreeNode* left;
TreeNode* right;
};
TreeNode* buildCompleteBinaryTree() {
TreeNode* root = new TreeNode{1};
root->left = new TreeNode{2};
root->right = new TreeNode{3};
root->left->left = new TreeNode{4};
root->left->right = new TreeNode{5};
root->right->left = new TreeNode{6};
return root;
}