问题 单项选择题

下列排序方法中,最坏情况下比较次数最少的是()。

A.冒泡排序

B.简单选择排序

C.直接插入排序

D.堆排序

答案

参考答案:D

解析:

冒泡排序、简单选择排序和直接插入排序法在最坏的情况下比较次数为:n(n-1)/2。而堆排序法在最坏的情况下需要比较的次数为O(nlog2n)。

阅读理解

阅读理解。

Dear Peter,

     My name is Frank.I am from(来自)America.Here is a picture of my class(班).We are in Class

One, Grade Seven.

     You can see my friends in the picture.Jimmy likes to play basketball.He likes to eat apples and

French fries.Helen likes math.Her favourite food is hamburgers.Sandra doesn't like math.But

shecan speak French(法语).She likes ping-pong.Sally is a black(黑人的) girl.She likes to swim

(游泳).She likes to eat ice cream.I like math too.Can you find(寻找) me? I like to eat bananas.

Maria likes computer very much.She plays computer games very well.Nick is fun.He can play

football.He likes strawberries best.

     Can you send(发送)me a picture of your class?

                                                                                                                                           Yours,

                                                                                                                                            Frank

1.Frank has    __    friends.

A.seven

B.six

C.five

2.___     like sports.

A.Jimmy, Sandra and Sally

B.Maria, Nick and Jimmy  

C.Sally, Nick, Jimmy and Sandra

3.    ___ and  ___    like math. 

A.Helen; Frank  

B.Sandra; Peter  

C.Helen; Sandra

4.    ___ and  ___    like fruit. 

A.Nick, Maria; Jimmy  

B.Nick, Frank; Peter  

C.Jimmy, Nick; Frank

5. ___    is the e-friend of Frank.

A.Sally

B.Sandra

C.Peter

选择题