alibaba笔试

1.D 

A(7,7)/(A(3,3)A(2,2)) = 420

关联：

字符串的排列和组合：http://blog.csdn.net/hackbuteer1/article/details/7462447

2.A

#include <iostream>

class Base
{
public:
    int Bar(char x) {
        printf("Bar(char x)\n");
        return (int) x;}
    virtual int Bar(int x){
        printf("virtual int Bar(int x)\n");
        return (*x);}
};

class Derived: public Base
{
public:
    int Bar(char x){
        printf("Derived Bar(char x)\n");
        return (int)(-x);}
    int Bar(int x) {
        printf("Derived Bar(int x)\n");
        return (x/);}
};

void main()
{
    Derived Obj;
    Base *pObj = &Obj;
    printf("%d\n", Obj.Bar((char)()));
    printf("%d\n", Obj.Bar());
    printf("%d\n", pObj->Bar((char)()));
    printf("%d\n", pObj->Bar());
    system("pause");
}

关联：

c++继承：公有，私有，保护：http://www.cnblogs.com/qlwy/archive/2011/08/25/2153584.html

c++  与Java的继承区别之一：http://hankjin.blog.163.com/blog/static/3373193720109892556114/

3.C

4.C

关联：

线性表：http://baike.baidu.com/view/178622.htm

关联数组：http://zh.wikipedia.org/wiki/%E5%85%B3%E8%81%94%E6%95%B0%E7%BB%84

类似于python中的字典