问题 单项选择题

对连通图进行遍历前设置所有顶点的访问标志为false(未被访问),遍历图后得到一个遍历序列,初始状态为空。深度优先遍历的含义是:从图中某个未被访问的顶点v出发开始遍历,先访问v并设置其访问标志为true(已访问),同时将v加入遍历序列,再从v的未被访问的邻接顶点中选一个顶点,进行深度优先遍历;若v的所有邻接点都已访问,则回到v在遍历序列的直接前驱顶点,再进行深度优先遍历,直至图中所有顶点被访问过。()是下图的深度优先遍历序列。

A.1 2 3 4 6 5

B.1 2 6 3 4 5

C.1 6 2 5 4 3

D.1 2 3 4 5 6

答案

参考答案:A

解析:

[分析]: 本题考查数据结构基础知识。

从顶点1出发进行深度优先遍历,接下来访问顶点2或顶点6,若是顶点2,则接着访问顶点3或4。根据图中的邻接关系,顶点4之后是顶点6,因此题中的4个选项中,123465是可能的深度优先遍历序列。

选择题
完形填空

第二节 简答题(共3小题;每小题2分,满分6分)

阅读下面的短文,并根据短文后的要求答题。(请注意问题后的字数要求)

Most young people enjoy some form of physical activity. It may be walking, cycling, or swimming, or in winter, skating or skiing. It may be a game of some form---football, basketball, hockey, golf or tennis. It may be mountaineering.

Those who have a passion for climbing high and difficult mountains are often looked upon with astonishment. Why are men and women willing to suffer cold and hardship, and to take risks(冒险) in high mountains? This astonishment is caused, probably, by the difference between mountaineering and other forms of activity to which men give their leisure(闲暇).

Mountaineering is a sport and not a game. There are no man-made rules as others, as there are for such games as golf and football. There are, of course, rules of different kind which it would be dangerous to ignore忽视), but it is this freedom from man-made rules that makes mountaineering attractive to many people. Those who climb mountains are free to use their own methods.

If we compare mountaineering and other more familiar sports, we might think that one big difference is that mountaineering is not a “team game”. We should be mistaken in this. There are, it is true, no “matches” between “teams” of climbers, but when climbers are on a rock face linked by a rope on which their lives may depend, there is obviously teamwork.

The mountain climber knows that he may have to fight forces that are stronger and more powerful than man. He has to fight the forces of nature. His sport requires high mental and physical qualities.

A mountain climber continues to improve in skill year after year. A skier is probably past his best by the age of thirty. But it is not unusual for men of fifty or sixty to climb the highest mountains in the Alps. They may take more time than younger men, but they perhaps climb with more skill and less waste of effort, and they certainly experience equal enjoyment.

70.According to the passage, what movements are popular among people in winter?(回答不超过5个单词)

71.What is the best title (标题) for this passage ? (回答不超过4个单词)

72. When do climbers work like a team while climbing ?(回答不超过12个单词)