单选题库

int countLeafNodes(TreeNode* root) {
    if (root == nullptr) return 0;
 
    stack<TreeNode*> s;
    s.push(root);
    int count = 0;
    while (!s.empty()) {
        TreeNode* node = s.top();
        s.pop();
 
        if (node->left == nullptr && node->right == nullptr) {
            count++;
        }
 
        if (node->right) s.push(node->right);
        ________________________ // 在此处填入代码
    }
    return count;
}

class CircularQueue {
    int* arr;
    int front, rear, size;
public:
    CircularQueue(int k) {
        size = k;
        arr = new int[k];
        front = rear = -1;
    }
 
    bool enQueue(int value) {
        if (isFull()) return false;
        if (isEmpty()) front = 0;
        rear = (rear + 1) % size;
        arr[rear] = value;
        return true;
    }
};

class MyClass {
public:
    MyClass() {
        cout << "Constructor called!" << endl;
    }
};
 
int main() {
    MyClass obj1;
    MyClass obj2 = obj1;
    return 0;
}