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)
");
        return (int) x;}
    virtual int Bar(int x){
        printf("virtual int Bar(int x)
");
        return (2*x);}
};

class Derived: public Base
{
public:
    int Bar(char x){
        printf("Derived Bar(char x)
");
        return (int)(-x);}
    int Bar(int x) {
        printf("Derived Bar(int x)
");
        return (x/2);}
};

void main()
{
    Derived Obj;
    Base *pObj = &Obj;
    printf("%d
", Obj.Bar((char)(100)));
    printf("%d
", Obj.Bar(100));
    printf("%d
", pObj->Bar((char)(100)));
    printf("%d
", pObj->Bar(100));
    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