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关于�U�瑟夫环的问题，�~�不下去了，那位帮忙看看

Tue, 12 Dec 2006 14:59:00 GMT

实验一�?span lang="EN-US">Joseph问题

问题描述 �Q�约瑟夫(Joseph)问题的一�U�描�q�是�Q�编号�ؓ1�Q?span lang="EN-US">2�Q?。。。，n�?span lang="EN-US">n个�h按顺旉��方向围坐一圈，每�h持有一个密码（正整敎ͼ�。一开始�Q选一个正整数作�ؓ报数上限�?span lang="EN-US">m�Q�从�W�一个�h开始按��时针方向自1开始顺序报敎ͼ�报到m时停止报数。报�?span lang="EN-US">m的�h出列�Q�将他的密码作�ؓ新的m��|��从他在顺旉��方向上的下一个�h开始重��C��1报数�Q�如此下去，直到所有�h全部出列为止。试设计一个程序求出出列顺序�?br />
�q�是我们数据�l�构�W�一个实验题目。大部分都用C语言写。我用C++写的�Q�写��C��半编译通过了，run的时候出了问题。还没有写完�Q�只把用用到的类写了出来。第一�ơ这样写�Q�不知道那里除了问题�?br />
代码�Q?br />

  1 #include " iostream.h "
  2 // #include "String.h"
  3
  4
  5
  6 class PersonList;
  7 class Joseph;
  8
  9 class Person {
10 // friend PersonList;
11 private :
12     char num;
13     int value;
14    // Person *next;
15 public :
16 Person * next;
17 Person();
18     Person( char , int );
19     Person(Person   & A);
20 } ;
21
22 Person::Person( char A, int Val)
23 {
24     num = A;
25     value = Val;
26
27 }
28 Person::Person(Person & B)
29 {
30     num = B.num;
31     value = B.value;
32     next = B.next;
33 }
34 class PersonList {
35 friend Joseph;
36 public :
37     Person * head, * tail;
38 int sum;
39 public :
40     PersonList();
41      ~ PersonList();
42      void initialPL();
43      void insertPl(PersonList & Pl,Person x);
44      void DeleteBlPerson(Person y);
45      bool NEmpty();
46 } ;
47
48 PersonList::PersonList()
49 {
50 Person * head = new Person;
51 Person * tail = head;
52
53 }
54
55 void PersonList::insertPl(PersonList & PL,Person x)
56 {
57     Person * p = new Person(x);
58     PL.tail -> next = p;
59     PL.tail = p;
60     PL.tail -> next = head;
61
62 }
63 void PersonList::DeleteBlPerson(Person y)
64 {
65     Person p =* y.next;
66 y.next = y.next -> next;
67
68 }
69
70
71 class Joseph {
72 private :
73 PersonList List;
74
75 public :
76 char * JosephList;   //用来存放输出序列
77 Joseph();
78
79
80 } ;
81
82 Joseph::Joseph()
83 {
84 PersonList P;
85 P.initialPL();
86 cout << " 人数 : " << endl;
87 cin >> P.sum;
88 for ( int i = P.sum;i > 0 ;i -- )
89 {
90   cout << " 代号 " << endl;
91    char a;
92   cin >> a;
93   cout << " �?/span> " << endl;
94    int x;
95   cin >> x;
96   Person Z(x,a);
97   P.insertPl(P,Z);
98 }
99
100
101 }
102
103
104
105 int main()
106 {
107     Joseph B;
108     cout << " 输入 " ;
109
110
111      return 0 ;
112 }
113

华剑�~?/a> 2006-12-12 22:59 发表评论

在C++学习上遇到的问题�Q�一�Q?关于this指针

Thu, 10 Aug 2006 06:53:00 GMT

this指针只能在一个类的成员函��C��调用�Q�它表示当前对象的地址。下面是一个例子：
    void Date::setMonth( int mn )
    {
     month = mn; // �q�三句是�{��h�?
     this->month = mn;
     (*this).month = mn;
    }

1. this只能在成员函��C��使用�?br />全局函数�Q�静态函数都不能使用this�?br />实际上，成员函数默认�W�一个参��CؓT* const register this�?br />如：
class A{public: int func(int p){}};
其中�Q�func的原型在�~�译器看来应该是�Q?int func(A* const register this, int p);

2. 由此可见�Q�this在成员函数的开始前构造的�Q�在成员的结束后清除�?br />�q�个生命周期同�Q一个函数的参数是一��L��Q�没有�Q何区别�?br />当调用一个类的成员函数时�Q�编译器��类的指针作为函数的this参数传递进厅R��如�Q?br />A a;
a.func(10);
此处�Q�编译器��会�~�译成： A::func(&a, 10);
嗯，看�v来和静态函数没差别�Q�对吗？不过�Q�区别还是有的。编译器通常会对this指针做一些优化的�Q�因此，this指针的传递效率比较高�Q�－如vc通常是通过ecx寄存器来传递this参数�?/p>

3. 回答
#1:this指针是什么时候创建的?
this在成员函数的开始执行前构造的�Q�在成员的执行结束后清除�?br />#2:this指针存放在何�? �?�?全局变量,�q�是其他?
this指针会因�~�译器不同，而放�|�的位置不同。可能是栈，也可能是寄存器，甚至全局变量�?br />#3:this指针如何传递给�c�M��函数�?�l�定?�q�是在函数参数的首参数就是this指针.那么this指针又是如何扑ֈ��c�d��例后函数�?
this是通过函数参数的首参数来传递的。this指针是在调用之前生成的。类实例后的函数�Q�没有这个说法。类在实例化�Ӟ��只分配类中的变量�I�间�Q��ƈ没有为函数分配空间。自从类的函数定义完成后�Q�它��在那儿�Q�不会跑的�?br />#4:this指针如何讉K��c�M��变量�??
如果不是�c�，而是�l�构的话�Q�那么，如何通过�l�构指针来访问结构中的变量呢�Q�如果你明白�q�一点的话，那就很好理解�q�个问题了�?br />在C++中，�c�d��l�构是只有一个区别的�Q�类的成员默认是private�Q�而结构是public�?br />this是类的指针，如果换成�l�构�Q�那this��是�l�构的指针了�?/p>

#5:我们只有获得一个对象后,才能通过对象使用this指针,如果我们知道一个对象this指针的位�|�可以直接��用吗?
this指针只有在成员函��C��才有定义。因此，你获得一个对象后�Q�也不能通过对象使用this指针。所以，我们也无法知道一个对象的this指针的位�|�（只有在成员函数里才有this指针的位�|�）。当�Ӟ��在成员函数里�Q�你是可以知道this指针的位�|�的�Q�可�?amp;this获得)�Q�也可以直接使用的�?br />#6:每个�cȝ��译后,是否创徏一个类中函数表保存函数指针,以便用来调用函数?
普通的�c�d��敎ͼ�不论是成员函敎ͼ��q�是静态函敎ͼ��Q�都不会创徏一个函数表来保存函数指针的。只有虚函数才会被放到函数表中�?br />但是�Q�既使是虚函敎ͼ�如果�~�译器能明确知道调用的是哪个函数�Q�编译器��׃��会通过函数表中的指针来间接调用�Q�而是会直接调用该函数�?/p>

# 7:�q�些�~�译器如何做到的?8:能否模拟实现?
知道原理后，�q�两个问题就很容易理解了�?br />其实�Q�模拟实现this的调用，在很多场合下�Q�很多�h都做�q��?br />例如�Q�系�l�回调函数。系�l�回调函数有很多�Q�如定时�Q�线�E�啊什么的�?/p>

举一个线�E�的例子�Q?br />class A{
int n;
public:
static void run(void* pThis){
A* this_ = (A*)pThis;
this_->process();
}
void process(){}
};

main(){
A a;
_beginthread( A::run, 0, &a );
}

�q�里��是定义一个静态函数来模拟成员函数�?/p>

也有许多C语言写的�E�序�Q�模拟了�cȝ��实现。如freetype库等�{��?br />其实�Q�有用过C语言的�h�Q�大多都模拟�q�。只是当时没有明��的概念�|�了�?br />如：
typedef struct student{
int age;
int no;
int scores;
}Student;
void initStudent(Student* pstudent);
void addScore(Student* pstudent, int score);
...
如果你把 pstudent�Ҏ��this�Q�那��׃��样了�?/p>

它相当于�Q?br />class Student{
public:
int age; int no; int scores;
void initStudent();
void addScore(int score);
}

const帔R��可以有物理存攄��I�间�Q�因此是可以取地址�?/p>

///this指针是在创徏对象前创�?
this指针攑֜�栈上,在编译时��d��l�确�?
�q�且当一个对象创建后,�q�且�q�行整个�E�序�q�行期间只有一个this指针.

华剑�~?/a> 2006-08-10 14:53 发表评论

用直接三角分解法求方�E�组的解

Tue, 30 May 2006 13:22:00 GMT

摘要: /**/ /////////////////////////////////////// / // //// ////数值分析直接三角分... 阅读全文

华剑�~?/a> 2006-05-30 21:22 发表评论

做题的意�?By EmilMatthew 06/04/16

Mon, 15 May 2006 15:01:00 GMT

做题的意�?/span>

By EmilMatthew 06/04/16

我可以有相当的理由，认�ؓ自己是一个喜爱学习的人，但是�Q�我亦不得不承认�Q�我的这份对学习的热爱是有所偏失的，自然也就无法享受到学习的全然乐趣。尤其在做到一些稍隄��问题的时候，镉K��是久��M��下，于是心生疑问�Q�我�q�等热情的投入学习，怎�ؓ何还无法��L��克难题，体会一些学�U�精妙之处�?/font>

实际�Q�这是一个谬误，��d��N��Q�除了有 PASSION �Q�有知识上的�U�篏�Q�更为关键的�Q�需要的是一�U�思维能力。而这�U�思维能力�Q�对于理工科的学习而言�Q�做题是个必不可��的环节。有 PASSION �Q�喜�Ƣ看书是我的现状�Q�这是好事情�Q�但�q�绝不是��_��有了�q�些��׃��定会有好的思维能力�Q�虽然好�?/span> PASSION 可以��L��发一定的思维力，但好的思维力却是必��要有训�l�的�q�一环节的，否则�Q�就会像一层窗��L��Q�一捅就��_��l�不��h��隑ֺ��Q�有深度问题的考验�?/span>

自从�q�了大学后，实际上我对考试的热情是逐渐下降的，对什么�ؓ考试而准备，忙的不可开焦之�cȝ��事甚��Z��ѝ��的��，��C��大学�q��ؓ考试而学习却实没什么意思，但是由厌恶考试而顺带着产生厌恶做题的情�l�就是个很不好的�l�果了。其实我的学习热情一直是高涨的，��其是大一感受了程序设计的��妙之后�Q�更是曾�l�一度�ؓ之废寝忘食，再加上我对物理及数学那点或发自内心的或出于敬仰的喜爱�Q�我对去解决一些有实际背景的问题还是充满热情的�Q�每当能发现自己要能发现些或创造什么小成果的时候，更是令�h心潮澎湃。但是，我对解题�Q�也��是做传�l�的书面上的试题却一直提不�v�_��Q�尽��多数的题目自己是解得下来的�Q�但是每当面寚w��题时�Q�我仍旧是力不从心的。而且�Q�我也发玎ͼ�在自��q��书的时候，很多最关键的证明，推导都相当的吃力。比如自动机的一些理论，较难的证明看几眼��开始晕了；再如��法分析理论斚w��的证明，很多时候也都是望而却步。究其原因，我想�Q�最关键的一点，��是�q�其中的一个整体思�\令�h无法把握。而这思�\�Q�恰恰是思维�q�程的一个体玎ͼ�光有知识的积累是�q�远不够的，解题是思维能力训练的一个至关重的环节。高中是也许�׃��q�度的应试对解题心生厌倦了�Q�但是到了大学里�Q�如果你惛_��得深入的话对解题仍旧不能有丝毫的松懈�?/span>

��M��Q�更多的时候是侧重吸收与理解，对于理工�U�类的书�c�而言�Q�读书是否读的透还与一个�h的思维能力有着相当的关联。在仅知道向量及�U�性代数的基础上看张量的概念，有的人看的不知所云，有的��Z��知半�?/span> ( 我就属于�q�种 ) �Q�有的�h一看就懂了�Q�再如一些力学中的分析及演算�Q�对于学的不扎实的�h来说�Q�可能把各个��步骤分解了看都懂是怎么回事�Q�可以综合到一��P��很隄��Z��所以然了。究其原因，在读书能力基本一致的前提下，关键��是看你在看到这��L��一个概念阐�q�的时候，你在思维上能对它做出怎样的反应。而这�U�思维上反应的高下�Q�和��M��一��P��也是要有一个积累的�q�程的，而这�U�过�E�的�U�篏�Q�在我看来，很大一部分��是通过做题来提高的�?/span>

思维的过�E�有归纳�Q�推理，演绎�Q�发散等许多方式�Q�我们对某个问题的解��x��意识和无意识中都用到了这些思维�q�程。无论是实际的工�E�问题，抑或是抽象出来的问题�Q�如习题�Q�思维能力��L��臛_��重要的作用。当�Ӟ��知识的积累在解决问题的过�E�中亦是举��轻重的。用唯物论的观点来看�Q�二者的关系是相辅相承的。工�E�的�Q�实际的问题相对要复杂和冗繁�Q�但未必都很艰深�Q�而习题中的抽象问题规模相对小�Q�对问题的剖析能辑ֈ�相当的深度。所以，��M��一个有理性思考的人都可以看到�Q�在学校把解决问题的基础打好了，无论是以后做研究�q�是��L��入到生��实践中去�Q�不说游刃有余，最��L��Q�在�l�过一定的适应后，是完全可以掌控的。而通过习题在思维层上的训�l�，更是可以使你在理工科 ---- �q�样一个富于理性化分析�Q�精巧构建，高度技巧化的领域中辑ֈ�融会贯通，触类旁通的作用。所以，以前我放弃或轻视做题的行为是何等的可�W�！

之所以对解题提不起太多兴��，其中很大的一部分原因是由于多数情况下我们的解题处于一�U�被动的局面。也��是��_��被老师“追着赶”，在这样一�U�情�l�下解题�Q�一者难有好的心情，二者目的以完成��d��Z��Q�虽然能学到一些东西，但终�I�有些情非得已的意味。想有效而又快乐的解题，个�h认�ؓ最好的法子��是��d��出击�Q�自己去��N��来做�Q�不必多找，找一两本较好出版�C�或在某一斚w��特别有实力的学校出的书是肯定不会错的。然后，��是自己的解题，回顾与体会了。至于解题的多少只能是因��异了，�q�和你个人的实际情况有很大关联，但有一点，��是解题一定要投入�Q�一定要重视自己做的�q�些题的从哪个角度去考查思维力以及对知识的运用、掌握，否则�Q�妄想以多做题来辑ֈ�思维飞跃的想法是徒劳的。个��为，�q�学习的��d��性一旦被调动��h��之后�Q�你马上会感受到解题也竟然和看书一��P��有着许多收获的喜悦与惊奇。而从解题中可以直接得到的最为重要的好处在于�Q�一来你�Ҏ��门课�E�本�w�的体系和知识结构加�׃��理解和掌握；二来你的思维能力体系又得��C��再一�ơ的加强�Q�遇到新问题的时候（哪怕和原来的领域不相关�Q�，你的�z�跃的思�\也必定会�l�你带来解决问题的更多、更好的启示�?/span>

所以，作�ؓ一个理工科学生的你�Q�无论是以后惛_��U�研�Q�还是想��快投入生��实践�Q�思维能力是极光��要的�Q�而做题，则是其中的一条必�׃��路。当你真正投入时�Q�你会发玎ͼ�做题原来也可以这般的享受�?/span>

华剑�~?/a> 2006-05-15 23:01 发表评论

Fri, 21 Apr 2006 15:26:00 GMT

1.某公叔R��用公用电话传�?0�l�数据，每组数据必须由四位整数组成，数据在传递过�E�中是加密的�Q�加密规则如下：每组数据中的每位数字都加�?�Q�然后用和除�?0的余��C��替该数字�Q�再��第一位和�W�四位交换，�W�二位和�W�三位交换。编�E�输出加密前后的数据�?img src ="http://www.shnenglu.com/gogo649/aggbug/6057.html" width = "1" height = "1" />

华剑�~?/a> 2006-04-21 23:26 发表评论

Sat, 15 Apr 2006 08:52:00 GMT

2005囄��奖获得者��?/strong>

3�?日，ACM�Q�美国计��机学会�Q�决定将2005�q�图灵奖颁发�l�Peter Naur�Q�以表嘪他在设计Algol 60语言上的贡献。由于其定义的清晰性，Algol 60成�ؓ了许多现代程序设计语�a�的原型。在语法描述中广泛��用的BNF范式�Q�其中的“N”便是来自Peter Naur的名字。图灵奖被称为“计��科学界的诺贝尔奖”，它创立于1960�q�_��现在的奖�?0万美元，由Intel公司赞助。 �?/span>

详文如下�Q?/span>

SOFTWARE PIONEER PETER NAUR WINS ACM'S TURING AWARD

Dane's Creative Genius Revolutionized Computer Language Design

New York, March 01, 2006 -- The Association for Computing Machinery (ACM) has named Peter Naur the winner of the 2005 A.M. Turing Award. The award is for Naur's pioneering work on defining the Algol 60 programming language. Algol 60 is the model for many later programming languages, including those that are indispensable software engineering tools today. The Turing Award, considered the "Nobel Prize of Computing" was first awarded in 1966, and is named for British mathematician Alan M. Turing. It carries a $100,000 prize, with financial support provided by Intel Corporation.

Dr. Naur was editor in 1960 of the hugely influential "Report on the Algorithmic Language Algol 60." He is recognized for the report's elegance, uniformity and coherence, and credited as an important contributor to the language's power and simplicity. The report made pioneering use of what later became known as Backus-Naur Form (BNF) to define the syntax of programs. BNF is now the standard way to define a computer language. Naur is also cited for his contribution to compiler design and to the art and practice of computer programming.

"Dr. Naur's ALGOL 60 embodied the notion of elegant simplicity for algorithmic expression," said Justin Rattner, Intel senior fellow and Chief Technology Officer. "Over the years, programming languages have become bloated with features and functions that have made them more difficult to learn and less effective. This award should encourage future language designers who are addressing today's biggest programming challenges, such as general-purpose, multi-threaded computation, to achieve that same level of elegance and simplicity that was the hallmark of ALGOL 60."

Contributions Signal Birth of Computing Science

In 2002, former Turing Award winner Edsger Dijkstra characterized the development of Algol 60 as "an absolute miracle" that signaled the birth of what he called "computing science" because it showed the first ways in which automatic computing could and should become a topic of academic concern. The development of Algol 60 was the result of an exceptionally talented group of people, including several who were later named Turing Award winners.

Dr. Naur's contribution to Algol 60, was seminal. John Backus, another former Turing Award winner, acknowledged Naur as the driving intellectual force behind the definition of Algol 60. He commented that Naur's editing of the Algol report and his comprehensive preparation for the January 1960 meeting in which Algol was presented "was the stuff that really made Algol 60 the language that it is, and it wouldn't have even come about, had he not done that."

Before publication of the Algol 60 Report, computer languages were informally defined by their prose manuals and the compiler code itself. The report, with its use of BNF to define the syntax, and carefully chosen prose to define the semantics, was concise, powerful, and unambiguous.

The 17-page Algol 60 Report presented the complete definition of an elegant, transparent language designed for communication among humans as well as with computers. It was deliberately independent of the properties of any particular computer. The new language was a major challenge to compiler writers. Dr. Naur went on to co-author the GIER Algol Compiler (for the transistorized electronic computer developed in Denmark known as GIER), one of the first compilers to deal fully and correctly with the language's powerful procedure mechanism.

"Dr. Naur's contribution was a watershed in the computing field, and transformed the way we define programming languages," said James Gray of Microsoft Research, and Chair of the 2005 Turing Committee. "Many of the programming constructs we take for granted today were introduced in the Algol Report, which introduced a concise block-structured language that improved the way we express algorithms."

Dr. Naur was instrumental in establishing software engineering as a discipline. He made pioneering contributions to methodologies for writing correct programs through his work on assertions that enable programmers to state their assumptions, and on structured programming. "His work, though formal and precise, displays an exceptional understanding of the limits and uses of formalism and precision," said Gray. Through these activities, and his development of an influential computer science curriculum, Dr. Naur contributed fundamental components of today's computing knowledge and skills.

Early Experience in Practical Calculations and Applications

Dr. Naur began his scientific pursuits as an astronomer, where he was involved in computations of the orbits of comets and minor planets. He obtained a magister of science degree (the equivalent of a master's degree) from Copenhagen University in 1949. He later returned there to earn a doctorate in astronomy in 1957. During the 1950-51 academic year, Dr. Naur studied astronomy at King's College in Cambridge, U.K., and came to the U.S. to further his work in the field. This work involved using early computers (starting with EDSAC, the world's first practical stored program electronic computer) for his astronomical calculations. In 1953, he returned to Denmark and served as a scientific assistant at Copenhagen Observatory.

In 1959, he joined the staff of the compiler design group at Regnecentralen, the first Danish computer company. There he organized the Algol Bulletin and was editor of the 13-person international Algol 60 team's report that defined Algol 60. He became a professor at the Copenhagen University Institute of Datalogy in 1969, retiring in 1998.

Dr. Naur was awarded the G. A. Hagemann Gold Medal from the Danish Technical University in 1963, the Jens Rosenkjaer Prize from the Danish Radio in 1966, and the Computer Pioneer Award from the Institute of Electrical and Electronics Engineers in 1986.
ACM will present the Turing Award at the annual ACM Awards Banquet on May 20, 2006, at the Westin St. Francis Hotel in San Francisco, CA.

About the A.M. Turing Award

The A.M. Turing Award was named for Alan M. Turing, the British mathematician who articulated the mathematical foundation and limits of computing, and who was a key contributor to the Allied cryptanalysis of the German Enigma cipher during World War II. Since its inception, the Turing Award has honored the computer scientists and engineers who created the systems and underlying theoretical foundations that have propelled the information technology industry. For additional information, please see the A. M. Turing Awards site.

About ACM

ACM, the Association for Computing Machinery (http://www.acm.org), is an educational and scientific society uniting the world's computing educators, researchers and professionals to inspire dialogue, share resources and address the field's challenges. ACM strengthens the profession's collective voice through strong leadership, promotion of the highest standards, and recognition of technical excellence. ACM supports the professional growth of its members by providing opportunities for life-long learning, career development, and professional networking.

华剑�~?/a> 2006-04-15 16:52 发表评论

Tue, 11 Apr 2006 05:22:00 GMT

摘要: [求助] 关于拯��构造函敎ͼ�对象传递！�Q?include < iostream.h > class Matrix { private : int ... 阅读全文

华剑�~?/a> 2006-04-11 13:22 发表评论

Sun, 09 Apr 2006 14:58:00 GMT

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#include " iostream.h "

int main()
{
         int N,i,j,count;
        cout << " Please enter N: " ;
        cin >> N;
         int ** arr = new int * [N];
         for (i = 0 ;i < N;i ++ )
                arr[i] = new int [N];
         for (i = 0 ;i < N;i ++ )
                 for (j = 0 ;j < N;j ++ )
                        arr[i][j] = 0 ;
        arr[ 0 ][(N + 1 ) / 2 - 1 ] = 1 ;
         for (count = 1 ,i = 0 ,j = (N + 1 ) / 2 - 1 ;count < N * N;count ++ )
         {
                i -- ;
                j -- ;
                 if (i ==- 1 )
                        i = N - 1 ;
                 if (j ==- 1 )
                        j = N - 1 ;
                 if (arr[i][j] == 0 )
                        arr[i][j] = count + 1 ;
                 else if (arr[i][j] > 0 )
                 {
                        i = i + 2 ;
                        j = j + 1 ;
                         if (j == N)
                                j = 0 ;
                         if (i == N)
                                i = 0 ;
                         else if (i == N + 1 )
                                i = 1 ;
                        arr[i][j] = count + 1 ;
                }
        }
         for (i = 0 ;i < N;i ++ )
         {
                 for (j = 0 ;j < N;j ++ )
                 {
                        cout << arr[i][j] << " " ;
                }
                cout << " \n " ;
        }
                      for (i = 0 ;i < N;i ++ )
                delete [] arr[i];
        delete [] arr;
         return 1 ;
}

华剑�~?/a> 2006-04-09 22:58 发表评论