C++ Primer Chapter 15 OOP

• Author: rin
• Time: October 14, 2021
• Classification: C++
• comment

<trans data-src="# Ch15 OOP"># Ch15 OOP</trans> <trans data-src="## 15.1 An Overview">## 15.1 An Overview</trans> <trans data-src="OOP is based on 3 fundamental concepts:">OOP is based on 3 fundamental concepts:</trans> <trans data-src="1. **Data abstraction**: Separate interface from implementation">1. **Data abstraction**: Separate interface from implementation</trans> <trans data-src="2. **Inheritance**: Define classes that model the relationships among similar types.">2. **Inheritance**: Define classes that model the relationships among similar types.</trans> <trans data-src="3. **Dynamic binding**(run-time binding): Use objects(*virtual function*) while ignoring the details of thow they differ (through *pointers* or *references* to the base class).">3. **Dynamic binding**(run-time binding): Use objects(*virtual function*) while ignoring the details of thow they differ (through *pointers* or *references* to the base class).</trans> <trans data-src="Inheritance:">Inheritance:</trans> <trans data-src="- A derived class must declare each inherited menber function it intends to override.">- A derived class must declare each inherited menber function it intends to override.</trans> <trans data-src="- The access specifier in derivation list is *optional*, default value = `private` for `class`, `public` for `struct`">- The access specifier in derivation list is *optional*, default value = `private` for `class`, `public` for `struct`</trans> <trans data-src="- A derived class ctor initializes its *direct* base class only.">- A derived class ctor initializes its *direct* base class only.</trans> <trans data-src="- Base part and derived part in an object are not guranteed to be stored contiguosly.">- Base part and derived part in an object are not guranteed to be stored contiguosly.</trans> <trans data-src="## 15.3 Virtual Function">## 15.3 Virtual Function</trans> <trans data-src="Virtual function:">Virtual function:</trans> <trans data-src="- Root of an inheritance hierarchy almost define a virtual dtor `virtual ~dtor(){}`.">- Root of an inheritance hierarchy almost define a virtual dtor `virtual ~dtor(){}`.</trans> <trans data-src="- Any *nonstatic* member func (other than ctor) can be virtual">- Any *nonstatic* member func (other than ctor) can be virtual</trans> <trans data-src="- If a virtul func with default args is called, which version of args to use is denpent on the static type. ">- If a virtul func with default args is called, which version of args to use is denpent on the static type. </trans> <trans data-src="Thus, such functions should use same default args. P607">Thus, such functions should use same default args. P607</trans> <trans data-src="- Virtual func declared in base class is implicitly virtual in derived classed: ">- Virtual func declared in base class is implicitly virtual in derived classed: </trans> <trans data-src="```c++">```c++</trans> <trans data-src="// inside base class:">// inside base class:</trans> <trans data-src="virtual void func() {}">virtual void func() {}</trans> <trans data-src="// inside derived class:">// inside derived class:</trans> <trans data-src="void func() = 0 // omitting keyword virtual is OK">void func() = 0 // omitting keyword virtual is OK</trans> <trans data-src="```">```</trans> <trans data-src="---">---</trans> <trans data-src="## 15.4 Abstract Base Classes">## 15.4 Abstract Base Classes</trans> <trans data-src="- We can provide a difinition for a *pure virtual* function (outside the class). ">- We can provide a difinition for a *pure virtual* function (outside the class). </trans> <trans data-src="It is used to provide some common operations. ">It is used to provide some common operations. </trans> <trans data-src="[c++ - Defining pure virtual functions outside the class definition - Stack Overflow](">[c++ - Defining pure virtual functions outside the class definition - Stack Overflow](</trans> <trans data-src="https://stackoverflow.com/questions/29449492/defining-pure-virtual-functions-outside-the-class-definition">https://stackoverflow.com/questions/29449492/defining-pure-virtual-functions-outside-the-class-definition</trans> <trans data-src=")">)</trans> <trans data-src="```c++">```c++</trans> <trans data-src="// outside the class">// outside the class</trans> <trans data-src="void B::func() { /*common operations */}">void B::func() { /*common operations */}</trans> <trans data-src="void B::~B() { /* some cleaning up *}">void B::~B() { /* some cleaning up *}</trans> <trans data-src="```">```</trans> <trans data-src="- Abstruct base class defines an *interface*">- Abstruct base class defines an *interface*</trans> <trans data-src="- A derived class ctor initializes its *direct* base class only.">- A derived class ctor initializes its *direct* base class only.</trans> <trans data-src="--- ">--- </trans> <trans data-src="## 15.5 Access Control & Inheritance">## 15.5 Access Control & Inheritance</trans> <trans data-src="- Members and **friends** of a derived class can access this (derived) class's protected members. ">- Members and **friends** of a derived class can access this (derived) class's protected members. </trans> <trans data-src="But the friends can't access the members of base class.">But the friends can't access the members of base class.</trans> <trans data-src="- In fact, a derived type object has no special access to the protected *ordinary* base type object.">- In fact, a derived type object has no special access to the protected *ordinary* base type object.</trans> <trans data-src="``` c++">``` c++</trans> <trans data-src="class B {">class B {</trans> <trans data-src="protected:">protected:</trans> <trans data-src="int v;">int v;</trans> <trans data-src="};">};</trans> <trans data-src="class D : public B {">class D : public B {</trans> <trans data-src="friend void func(D&); // ">friend void func(D&); // </trans> <trans data-src="can access D's protected member D::v">can access D's protected member D::v</trans> <trans data-src="friend void func(B&); // ">friend void func(B&); // </trans> <trans data-src="can't access B's protected member B::v">can't access B's protected member B::v</trans> <trans data-src="void func(B& b){b.v=1;} // no direct access to ordinary object's v">void func(B& b){b.v=1;} // no direct access to ordinary object's v</trans> <trans data-src="void func() {v=1;} // OK ">void func() {v=1;} // OK </trans> <trans data-src="};">};</trans> <trans data-src="```">```</trans> <trans data-src="### Dervied-to-Base Conversion">### Dervied-to-Base Conversion</trans> <trans data-src="Accessibility depends on *who* is using the conversion and the *access specifier* in derivation.">Accessibility depends on *who* is using the conversion and the *access specifier* in derivation.</trans> <trans data-src="1. The User Code: public">1. The User Code: public</trans> <trans data-src="2. The Member func and Friend func of the derived class: `public`, `protected`, `private`==<-why private works== #what ">2. The Member func and Friend func of the derived class: `public`, `protected`, `private`==<-why private works== #what </trans> <trans data-src="3. The Member func and Friend func of the derived class of derived class: `public`, `protected`">3. The Member func and Friend func of the derived class of derived class: `public`, `protected`</trans> <trans data-src="```c++">```c++</trans> <trans data-src="class B { protected: int v = 1; };">class B { protected: int v = 1; };</trans> <trans data-src="class D :/*__what to fill_____*/ B {">class D :/*__what to fill_____*/ B {</trans> <trans data-src="void member_func() {">void member_func() {</trans> <trans data-src="D d;">D d;</trans> <trans data-src="// CASE#2: derived-to-base conversion in MEMBER FUNC & FRIENDS">// CASE#2: derived-to-base conversion in MEMBER FUNC & FRIENDS</trans> <trans data-src="B b = (B)d; // ">B b = (B)d; // </trans> <trans data-src="OK: public, protected, private">OK: public, protected, private</trans> <trans data-src="}">}</trans> <trans data-src="friend void friend_func(); // ">friend void friend_func(); // </trans> <trans data-src="CASE#2: same for the FRIENDS">CASE#2: same for the FRIENDS</trans> <trans data-src="};">};</trans> <trans data-src="class AnotherClass : protected D {">class AnotherClass : protected D {</trans> <trans data-src="void func() {">void func() {</trans> <trans data-src="D d;">D d;</trans> <trans data-src="// CASE#3: derived-to-base conversion in the Class derived from D">// CASE#3: derived-to-base conversion in the Class derived from D</trans> <trans data-src="B b = (B)d; // ">B b = (B)d; // </trans> <trans data-src="OK: public, protected (both for the D->B and AC->D inheritance)">OK: public, protected (both for the D->B and AC->D inheritance)</trans> <trans data-src="}">}</trans> <trans data-src="};">};</trans> <trans data-src="int main() {">int main() {</trans> <trans data-src="D d;">D d;</trans> <trans data-src="// CASE#1: derived-to-base conversion in USER CODE">// CASE#1: derived-to-base conversion in USER CODE</trans> <trans data-src="B b = (B)d; // ">B b = (B)d; // </trans> <trans data-src="OK: only public">OK: only public</trans> <trans data-src="}">}</trans> <trans data-src="```">```</trans> <trans data-src="---">---</trans> <trans data-src="## 15.6 Class Scope under Inheritance">## 15.6 Class Scope under Inheritance</trans> <trans data-src="- Name Lookup happens before Type check. ">- Name Lookup happens before Type check. </trans> <trans data-src="The base functions are hidden even if the functions in derived class have different paramete list.">The base functions are hidden even if the functions in derived class have different paramete list.</trans> <trans data-src="- Once override one of the (Base class's) overloaded functions, other overloaded functions will be hiden. ">- Once override one of the (Base class's) overloaded functions, other overloaded functions will be hiden. </trans> <trans data-src="Use `using` to bring all versions:">Use `using` to bring all versions:</trans> <trans data-src="https://stackoverflow.com/questions/888235/overriding-a-bases-overloaded-function-in-c">https://stackoverflow.com/questions/888235/overriding-a-bases-overloaded-function-in-c</trans> <trans data-src="```c++">```c++</trans> <trans data-src="#include <iostream>">#include <iostream></trans> <trans data-src="using namespace std;">using namespace std;</trans> <trans data-src="struct B {">struct B {</trans> <trans data-src="virtual void a(int) { cout << "B::a(int)" << endl;};">virtual void a(int) { cout << "B::a(int)" << endl;};</trans> <trans data-src="virtual void a(int, int) { cout << "B::a(int,int)" << endl;};">virtual void a(int, int) { cout << "B::a(int,int)" << endl;};</trans> <trans data-src="};">};</trans> <trans data-src="struct D: public B {">struct D: public B {</trans> <trans data-src="void a(int) { cout << "D::a(int)" << endl;};">void a(int) { cout << "D::a(int)" << endl;};</trans> <trans data-src="void a(int,int,int){ cout << "D::a(int,int,int)" << endl;};;">void a(int,int,int){ cout << "D::a(int,int,int)" << endl;};;</trans> <trans data-src="using B::a; // ">using B::a; // </trans> <trans data-src="bring all overloded function from B">bring all overloded function from B</trans> <trans data-src="};">};</trans> <trans data-src="int main() {">int main() {</trans> <trans data-src="D d; ">D d; </trans> <trans data-src="int i = 0;">int i = 0;</trans> <trans data-src="d.a(i); // ">d.a(i); // </trans> <trans data-src="OK, D::a(int)">OK, D::a(int)</trans> <trans data-src="// d.a(i, i); // ">// d.a(i, i); // </trans> <trans data-src="NO matching function without `using`">NO matching function without `using`</trans> <trans data-src="d.B::a(i,i); // ">d.B::a(i,i); // </trans> <trans data-src="OK, B::a(int,int)">OK, B::a(int,int)</trans> <trans data-src="d.a(i, i, i); // ">d.a(i, i, i); // </trans> <trans data-src="OK, D::a(int,int,int)">OK, D::a(int,int,int)</trans> <trans data-src="}">}</trans> <trans data-src="```">```</trans> <trans data-src="---">---</trans> <trans data-src="## 15.7 Ctor and Copy Control">## 15.7 Ctor and Copy Control</trans> <trans data-src="- Use `using` to "inherit" ctors from a class's *direct* base class. ">- Use `using` to "inherit" ctors from a class's *direct* base class. </trans> <trans data-src="Compiler generates ctors with a same parameter list as the ctor in the base class.">Compiler generates ctors with a same parameter list as the ctor in the base class.</trans> <trans data-src="- Unlike `using` ordinary members, this doesn't change the ctors access level and propertirs(explict, constexpr)">- Unlike `using` ordinary members, this doesn't change the ctors access level and propertirs(explict, constexpr)</trans> <trans data-src="- Base ctors with default parameters are split into serveral ctors withou default parameters #what ">- Base ctors with default parameters are split into serveral ctors withou default parameters #what </trans> <trans data-src="- default copy, move ctors are not ingerited">- default copy, move ctors are not ingerited</trans> <trans data-src="- a class that only contains inherited ctors will have a synthesized default ctor.">- a class that only contains inherited ctors will have a synthesized default ctor.</trans> <trans data-src="-">-</trans>

Manacher instance

• Author: rin
• Time: July 18, 2020
• Classification: Unclassified
• comment

<trans data-src="[前坑](">[Front pit]（</trans> <trans data-src="https://lo-li.net/1311-manacher-%E7%AE%97%E6%B3%95%E6%B1%82%E6%9C%80%E9%95%BF%E5%9B%9E%E6%96%87%E5%AD%90%E4%B8%B2.html">https://lo-li.net/1311-manacher-%E7%AE%97%E6%B3%95%E6%B1%82%E6%9C%80%E9%95%BF%E5%9B%9E%E6%96%87%E5%AD%90%E4%B8%B2.html</trans> <trans data-src=")">)</trans> <trans data-src="!">!</trans> <trans data-src="[manacher2.png](">[manacher2.png](</trans> <trans data-src="https://static.lo-li.net/typecho/2020/07/2154660342.png">https://static.lo-li.net/typecho/2020/07/2154660342.png</trans> <trans data-src=")">)</trans> <trans data-src="符号说明：">Symbol description:</trans> <trans data-src="* `i`为字符串中的下标，`S`是预处理后的字符串">*'i' is the subscript in the string, and 'S' is the preprocessed string</trans> <trans data-src="* `P[i]`代表以`i`为中心（含）的地方，回文的半径长度。">*'P [i]' represents the radius length of palindrome where 'i' is the center (included).</trans> <trans data-src="例如`P[1]=1`意为以`'#'`为中心的最长回文子串为`"#"`，半径长度为1；">For example, 'P [1]=1' means that the longest palindrome substring centered on '#' is' # ', and the radius length is 1;</trans> <trans data-src="同样，`P[16]=4`意为以`'x'`为中心的最长回文子串`"#p#x#p#"`的半径`"#p#x"/"x#p#"`的长度4">Similarly, 'P [16]=4' means the length 4 of the radius' # p # x '/' x # p # 'of the longest palindrome substring' # p # x # p # 'centered on' x '</trans> <trans data-src="* `id`代表当前已知的最长回文子串的中点；`">*'id' represents the midpoint of the longest palindrome substring currently known`</trans> <trans data-src="mx`代表该子串的半径长度+1">Mx ` represents the radius length of the substring+1</trans> <trans data-src="* 带圈数字代表步骤">*Circled numbers represent steps</trans> <trans data-src="①、起始状态，`i=0,mx=0,id=0`">① , Start Status, ` i=0, mx=0, id=0`</trans> <trans data-src="此时`i=1 >= mx=0`，即此位置已经超过了已知的最长回文范围（因为才开始嘛），同时也能确定`P[1]=至少=1`。">At this time, 'i=1>=mx=0', that is, this position has exceeded the known longest palindrome range (because it just started). At the same time, it can be determined that 'P [1]=at least=1'.</trans> <trans data-src="因此现在需要以`i=1`为中心，从其半径范围外两边开始逐一比对。">So now we need to take 'i=1' as the center, and start the comparison one by one from both sides outside its radius.</trans> <trans data-src="（两边就是`i±P[i]`）">(The two sides are 'i ± P [i]')</trans> <trans data-src="发现`'$'≠'a'`，扩展不下去了便停止，更新`id=1,mx=id+P[id]=1+1=2`">If '$' ≠'a '' is found, the extension will stop and update 'id=1, mx=id+P [id]=1+1=2`</trans> <trans data-src="②、`i=2,mx=2,id=1`">②、`i=2,mx=2,id=1`</trans> <trans data-src="此时`i=2 >= mx=2`，同样超过了已知的最长回文范围（注意`mx`是边界+1），同理能确定`P[2]=至少=1`。">At this time, 'i=2>=mx=2', which also exceeds the known longest palindrome range (note that 'mx' is the boundary+1). Similarly, it can be determined that 'P [2]=at least=1'.</trans> <trans data-src="继续扩展发现`'#'='#'`，则`P[2]++`，再继续无法扩展`$≠b`。">If you continue to expand and find that '#'='#' ', then' P [2]++'can't be expanded' $≠ b '.</trans> <trans data-src="更新`id=2,mx=id+P[id]=2+2=4`">Update ` id=2, mx=id+P [id]=2+2=4`</trans> <trans data-src="③、`i=3,mx=4,id=2`">③、`i=3,mx=4,id=2`</trans> <trans data-src="此时`i < mx`了，说明`i`在**已知最长的回文子串（id=2的那个）**的势力范围内了。">At this time, 'i<mx' indicates that 'i' is within the sphere of influence of * * the longest palindrome string (the one with id=2) * *.</trans> <trans data-src="那么根据对称性，`i=3`在前面就有一个“分身”`j=2*id-i=1`">According to the symmetry, 'i=3' has a "avatar" in front of it ` j=2 * id-i=1`</trans> <trans data-src="现在想求的`P[i]`就和`P[j]`有一种关系：`P[i]`=**可能**=`P[j]`，那么此时以`i`为中心的回文子串最右的下标就**有可能**扩展到`i+P[i]-1`，例如此时：">The 'P [i]' you want to seek now has a relationship with 'P [j]': 'P [i]'=* * may * *='P [j]', then the right subscript of palindrome substring centered on 'i' will * * possibly * * extend to 'i+P [i] - 1', for example:</trans> <trans data-src="!">!</trans> <trans data-src="[manacher1.png](">[manacher1.png](</trans> <trans data-src="https://static.lo-li.net/typecho/2020/07/3248822752.png">https://static.lo-li.net/typecho/2020/07/3248822752.png</trans> <trans data-src=")">)</trans> <trans data-src="`i+P[i]-1=3+1-1=3 < mx=4`，`3`仍处在**能保证对称的<span style="background-color:#ffe699">势力范围内</span>**，那么上面的“可能”变成“一定”。">`I+P [i] - 1=3+1-1=3<mx=4 `, ` 3 ` is still within the scope of influence of * * to ensure symmetry<span style="background color: # ffe699"></span>* *, then the "may" above becomes "certain".</trans> <trans data-src="（当然现在串还太短效果不是很明显，可以参考后面的⑥；同时“不可能”的情况请参考文末）">(Of course, the current string is too short, and the effect is not obvious. Please refer to ⑥ below; in the case of "impossible", please refer to the end of the article.)</trans> <trans data-src="④、⑤同理">④ ⑤ Same reason</trans> <trans data-src="⑥、`i=6,mx=10,id=5`">⑥、`i=6,mx=10,id=5`</trans> <trans data-src="`P[6]=P[4]=2`，现在能从下标`6-2=4`和`6+2=8`的位置开始对比，而对称区域内的都不用再比了。">`P [6]=P [4]=2 `, now you can compare from the subscript '6-2=4' and '6+2=8', and no comparison is needed in the symmetric area.</trans> <trans data-src="所以就利用了已知的信息跳过了很多次对比。">So we use the known information to skip many comparisons.</trans> <trans data-src="然后`'b'≠'a'`停止，`6+2=8 < mx=10`，说明仍然处于最长的那个子串内部，所以不更新`mx,id`">Then ''b' ≠'a '' stops, '6+2=8<mx=10', indicating that it is still inside the longest substring, so 'mx, id' is not updated`</trans> <trans data-src="……">……</trans> <trans data-src="如此便能算出所有的`P[i]`并且能得到最长的长度。">In this way, all 'P [i]' can be calculated and the longest length can be obtained.</trans> <trans data-src="------------">------------</trans> <trans data-src="“不可能”的情况">"Impossible" situation</trans> <trans data-src="换一个例子">Another example</trans> <trans data-src="!">!</trans> <trans data-src="[manacher3.png](">[manacher3.png](</trans> <trans data-src="https://static.lo-li.net/typecho/2020/07/31183235.png">https://static.lo-li.net/typecho/2020/07/31183235.png</trans> <trans data-src=")">)</trans> <trans data-src="此时`i=11,id=8,mx=14`">At this time, ` i=11, id=8, mx=14`</trans> <trans data-src="根据预判，`P[11]=P[5]=5`。">According to the prediction, 'P [11]=P [5]=5'.</trans> <trans data-src="但是下标`11+5=16 >= mx=14`，预判超过了**能保证对称**的部分，于是剩余的部分`14,15`就要和`8,7`暴力对比。">But the subscript '11+5=16>=mx=14', the prediction exceeds the part that * * can guarantee symmetry * *, so the remaining part '14,15' will be compared with '8,7' violently.</trans>

[POJ1017]Packets

• Author: rin
• Time: February 1, 2017
• Classification: Algo
• 11 comments

<trans data-src="# 题目描述">#Title description</trans> <trans data-src="一家工厂生产的产品以相同的高$$h$$，六种不同的长宽$$1\*1,2\*2,3\*3,4\*4,5\*5,6\*6$$包装。">The products produced by one factory are packaged with the same height of $$h $$and six different lengths and widths of $$1 * 1,2 * 2,3 * 3,4 * 4,5 * 5,6 * 6 $$.</trans> <trans data-src="送货时集装的箱子的高也为$$h$$，长宽为$$6*6$$。">At the time of delivery, the height of the container is $$h $$, and the length and width are $$6 * 6 $$.</trans> <trans data-src="根据每种尺寸的产品的个数求出最少需要多少箱子来装。">According to the number of products of each size, find out the minimum number of boxes to be packed.</trans> <trans data-src="# 输入">#Input</trans> <trans data-src="输入包含多组数据">Input contains multiple sets of data</trans> <trans data-src="每组数据为一行六个数，分别代表边长$$1$$到$$6$$产品的个数。">Each group of data consists of six numbers in a row, representing the number of products with side length from $$1 $$to $$6 $$.</trans> <trans data-src="输入以六个$$0$$结束。">Input ends with six $$0 $$.</trans> <trans data-src="# 输出">#Output</trans> <trans data-src="每组数据输出一行一个数，代表最少需用的箱子个数。">Each group of data outputs one number per line, representing the minimum number of boxes needed.</trans> <trans data-src="# 样例输入">#Sample Input</trans> <trans data-src="```">```</trans> <trans data-src="0 0 4 0 0 1 ">0 0 4 0 0 1 </trans> <trans data-src="7 5 1 0 0 0 ">7 5 1 0 0 0 </trans> <trans data-src="0 0 0 0 0 0 ">0 0 0 0 0 0 </trans> <trans data-src="```">```</trans> <trans data-src="# 样例输出">#Sample Output</trans> <trans data-src="```">```</trans> <trans data-src="2">two</trans> <trans data-src="1">one</trans> <trans data-src="```">```</trans> <trans data-src="---">---</trans>

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Codeforces Round #384 (Div. 2)

• Author: rin
• Time: December 15, 2016
• Classification: Unclassified
• comment

<trans data-src="~~这个灰名选手一直坚持他蓝名梦想~~">~~This grey player has always adhered to his dream of becoming a blue star~~</trans> <trans data-src="------------">------------</trans> <trans data-src="[A. Vladik and flights](">[A. Vladik and flights](</trans> <trans data-src="http://codeforces.com/problemset/problem/743/A">http://codeforces.com/problemset/problem/743/A</trans> <trans data-src=")">)</trans> <trans data-src="有$$n$$个机场，要从$$a$$飞到$$b$$">There are $$n $$airports to fly from $$a $$to $$b$$</trans> <trans data-src="每个机场有航空公司$$0$$或$$1$$，同航空公司机场间移动无费用，不同的之间为$$|ni-nj|$$，问从$$a$$到$$b$$最少花费是多少。">Each airport has an airline of $$0 $$or $$1 $$. There is no cost for moving between airports of the same airline. The difference is $$| ni nj | $$. Ask what the minimum cost is from $$a $$to $$b $$.</trans> <trans data-src="因为同公司无费用，所以如果$$a$$和$$b$$地相同的话就输出$$0$$；">Because there is no cost in the same company, $$0 $$will be output if $$a $$and $$b $$are the same;</trans> <trans data-src="如果不相同，那么从$$a$$一定能移动到一个地方，是$$0$$和$$1$$的交界，然后在交界换一家公司飞到b，花费是$$1$$">If they are not the same, then they must be able to move from $$a $$to a place where $$0 $$and $$1 $$meet, and then fly from another company at the junction to b at a cost of $$1$$</trans> <trans data-src="```c++">```c++</trans> <trans data-src="int main(){">int main(){</trans> <trans data-src="int n, a, b;">int n, a, b;</trans> <trans data-src="char aType, bType;">char aType, bType;</trans> <trans data-src="scanf("%d %d %d", &n, &a, &b);">scanf("%d %d %d", &n, &a, &b);</trans> <trans data-src="getchar();">getchar();</trans> <trans data-src="for (int i = 1; i <= n; i++) {">for (int i = 1; i <= n; i++) {</trans> <trans data-src="if (i == a) scanf("%c", &aType);">if (i == a) scanf("%c", &aType);</trans> <trans data-src="else if (i == b) scanf("%c", &bType);">else if (i == b) scanf("%c", &bType);</trans> <trans data-src="else scanf("%*c");">else scanf("%*c");</trans> <trans data-src="}">}</trans> <trans data-src="puts((aType == bType || a == b) ? ">puts((aType == bType || a == b) ? </trans> <trans data-src=""0" : "1");">"0" : "1");</trans> <trans data-src="return 0;">return 0;</trans> <trans data-src="}">}</trans> <trans data-src="```">```</trans> <trans data-src="------------">------------</trans> <trans data-src="[B. Chloe and the sequence](">[B. Chloe and the sequence](</trans> <trans data-src="http://codeforces.com/problemset/problem/743/B">http://codeforces.com/problemset/problem/743/B</trans> <trans data-src=")">)</trans> <trans data-src="初始有一个序列$$[1]$$">There is initially a sequence $$[1]$$</trans> <trans data-src="然后将它本身加到后面变成$$[1,1]$$">Then add it to the end to become $$[1,1]$$</trans> <trans data-src="再将还未使用的最小的正整数加到正中的位置$$[1,2,1]$$">Add the smallest unused positive integer to the middle position $$[1,2,1]$$</trans> <trans data-src="重复$$n-1$$次">Repeat $$n-1 $$times</trans> <trans data-src="问这之后第$$k$$个数字是啥">Ask what is the $$k $$number after this</trans> <trans data-src="由~~观察瞎猜脑洞~~，~~可以看出~~，这个序列代表从$$1$$到某个数，(二进制)从右数起第一个$$1$$的位置，比如">From~~to observe the brain hole~~,~~, we can see that~~, this sequence represents the position of the first $$$from the right to a certain number, such as</trans> <trans data-src="| 数（二进制） | 1的位置 |">|Number (binary) | 1 position|</trans> <trans data-src="| ------------ | ------------ |">| ------------ | ------------ |</trans> <trans data-src="| 1(1) | 1 |">| 1(1) | 1 |</trans> <trans data-src="| 2(10) | 2 |">| 2(10) | 2 |</trans> <trans data-src="|3(11)|1|">|3(11)|1|</trans> <trans data-src="|4(100)|3|">|4(100)|3|</trans> <trans data-src="|5(101)|1|">|5(101)|1|</trans> <trans data-src="|6(110)|2|">|6(110)|2|</trans> <trans data-src="|...|...|">|...|...|</trans> <trans data-src="那么第$$k$$位是啥，就是$$k$$的右起第一个$$1$$位置。">Then what is the first $$$$from the right of $$k $$.</trans> <trans data-src="可以直接用glibc里的`__builtin_ffs()`函数">You can directly use the '__builtin_ffs()' function in glibc</trans> <trans data-src="考虑到$$k$$超`int`用其`long long`版本 ` __builtin_ffsll()`">Considering that $$k $$super 'int' uses its' long long 'version' __builtin_ffsll()`</trans> <trans data-src="```c++">```c++</trans> <trans data-src="int main(){">int main(){</trans> <trans data-src="long long k;">long long k;</trans> <trans data-src="scanf("%*lld %lld", &k);">scanf("%*lld %lld", &k);</trans> <trans data-src="printf("%d\n", __builtin_ffsll(k));">printf("%d\n", __builtin_ffsll(k));</trans> <trans data-src="return 0;">return 0;</trans> <trans data-src="}">}</trans> <trans data-src="```">```</trans>

[ICPC2016Dalian Onsite] Official explanation

• Author: rin
• Time: November 6, 2016
• Classification: Algo
• 7 comments

<trans data-src="[PDF版](">[PDF version]（</trans> <trans data-src="http://pan.baidu.com/s/1bpkkoTD">http://pan.baidu.com/s/1bpkkoTD</trans> <trans data-src=")">)</trans> <trans data-src="> 添加 `-D__STDC_FORMAT_MACROS`以支持`PRId64`">>Add '- D_STDC_FORMAT_MACROS' to support' PRId64`</trans> <trans data-src="#Problem A Wrestling Match">#Problem A Wrestling Match</trans> <trans data-src="##提交情况：170/434">##Submission: 170/434</trans> <trans data-src="##解题思路">##Solutions</trans> <trans data-src="本题做法比较随意，此处说两种：">The method of this question is quite casual. Here are two ways:</trans> <trans data-src="1. 读入数据，建好图以后，以每一个点为开始遍历的起始节点，搜索整个图，在搜索的过程中判断是否出现冲突">1. After reading data and building a graph, search the whole graph with each point as the starting node, and judge whether there is conflict in the process of searching</trans> <trans data-src="2. 用并查集维护题目中所谓『好选手』以及『坏选手』的关系，在建立并查集的过程中，就可判断冲突">2. Maintain the relationship between the so-called "good players" and "bad players" in the topic by using the combined search set. In the process of establishing and searching the set, conflicts can be judged</trans> <trans data-src="总的来说，第2种做法需要处理的特殊情况较少，并且计算量照第1种做法少，所以标程采用第2种做法。">In general, the second method needs to deal with fewer special cases, and the calculation amount is less according to the first method, so the second method is adopted for the scale.</trans>

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