摘要:老师让用中方式都实现一遍,分别是广度优先搜索深度优先搜索和启发式搜索。先分享深度优先搜索,后两篇我会分享广度优先搜索和启发式搜索的实现。
人工智能课,第一个实验就是八数码问题。老师让用3中方式都实现一遍,分别是广度优先搜索、深度优先搜索和启发式搜索。心塞╮(╯▽╰)╭。紧急补了一些数据结构的知识,就匆匆上阵。先分享深度优先搜索,后两篇我会分享广度优先搜索和启发式搜索的实现。
概念就不讲了,百度就行了。简单说一下我的实现:Situation类存储节点信息,包括父节点的code值(code是一个字符串,存储的是八数码的状态,比如“138427056”),当前节点的code值,以及深度(深度从0开始,即起始节点深度为0);在Test.cpp的main函数中,我定义了两个链表open和closed分别存放未被扩展的节点和被扩展的节点。深度优先,新生成的有效的子节点存放在open表的开头。每次扩展,拿open表的开头的那个节点来扩展,方法是把open表的头节点移动到closed表的末端,生成的最多4个有效的子节点存放在open表的开头。其他就是比较生成的节点和目标节点是否相等了。
以下代码在win8.1下VS2013中测试成功。
头文件Deep.h:
#include#include"queue" #include"string" #include using namespace std; const string GOAL = "803214765"; class Situation{ private: public: string father; string code;//当前状态 int deep; Situation up(); Situation down(); Situation left(); Situation right(); bool isGoal(); bool isInOpen(deque
&open); bool isInClosed(deque &closed); void show() const; void show(string) const; void show_deque(deque &) const; deque showWay(deque &closed); void showAnswer(deque &closed);//显示解答 Situation() :father(""), code(""), deep(-1){}; };
Deep.cpp:
#include"Deep.h" Situation Situation::up(){ string::size_type loc = code.find("0");//0的位置,从0开始计数 Situation son; son.code = code; son.deep = deep + 1; if (loc>=3){ char temp = son.code[loc];//即0 son.code[loc] = son.code[loc - 3]; son.code[loc-3] = temp; } else{ son.code = ""; } return son; } Situation Situation::down(){ string::size_type loc = code.find("0");//0的位置,从0开始计数 Situation son; son.code = code; son.deep = deep + 1; if (loc<=5){ char temp = son.code[loc];//即0 son.code[loc] = son.code[loc + 3]; son.code[loc + 3] = temp; } else{ son.code = ""; } return son; } Situation Situation::left(){ string::size_type loc = code.find("0");//0的位置,从0开始计数 Situation son; son.code = code; son.deep = deep + 1; if (loc!=0&&loc!=3&&loc!=6){ char temp = son.code[loc];//即0 son.code[loc] = son.code[loc - 1]; son.code[loc - 1] = temp; } else{ son.code = ""; } return son; } Situation Situation::right(){ string::size_type loc = code.find("0");//0的位置,从0开始计数 Situation son; son.code = code; son.deep = deep + 1; if (loc!=2&&loc!=5&&loc!=8){ char temp = son.code[loc];//即0 son.code[loc] = son.code[loc + 1]; son.code[loc + 1] = temp; } else{ son.code = ""; } return son; } bool Situation::isGoal(){ return code == GOAL; } bool Situation::isInOpen(deque&open){ /*deque ::iterator it = open.begin(); while (it != open.end()){ if (code == (*it).code){ return true; } it++; }*/ for (int i = 0; i < open.size();i++){ if (code==open.at(i).code){ return true; } } return false; } bool Situation::isInClosed(deque &closed){ /*deque ::iterator it = closed.begin(); while (it!=closed.end()){ if (code == (*it).code){ return true; } it++; }*/ for (int i = 0; i < closed.size(); i++){ if (code == closed.at(i).code){ return true; } } return false; } void Situation::show() const{ if (!code.empty()){ cout << code[0] << code[1] << code[2] << endl << code[3] << code[4] << code[5] << endl << code[6] << code[7] << code[8] << endl << endl; } else{ cout << "空的" << endl; } } void Situation::show(string code) const{ if (!code.empty()){ cout << code[0] << code[1] << code[2] << endl << code[3] << code[4] << code[5] << endl << code[6] << code[7] << code[8] << endl << endl; } else{ cout << "空的" << endl; } } void Situation::show_deque(deque &m_deque) const{ /*deque ::iterator it = m_deque.begin(); while (it!=m_deque.end()) { (*it).show(); it++; }*/ for (int i = 0; i < m_deque.size();i++){ m_deque.at(i).show(); } } //路径 deque Situation::showWay(deque &closed){ //cout << closed.size() << endl; deque dequeList; Situation temp = closed.back(); dequeList.push_back(temp); //closed表从后往前,根据father值找到路径 for (int i = closed.size()-1; i >= 0;i--){ if (temp.father==closed.at(i).code){ dequeList.push_back(closed.at(i)); temp = closed.at(i); } } //cout << dequeList.size() << endl; return dequeList; } void Situation::showAnswer(deque &closed){ deque way(showWay(closed)); cout << "共需要" << way.size() << "步" << endl; for (int i = way.size() - 1; i >= 0; i--) { way.at(i).show(); } //输出目标 show(GOAL); }
Test.cpp:
#include#include"Deep.h" using namespace std; void loop(deque &open, deque &closed, int range); int main(){ string original = "283164705"; Situation first; deque open, closed;//open存放未扩展节点,closed存放已扩展节点 int range = 10;//深度界限 first.code = original; first.deep = 0; open.push_back(first); loop(open,closed,range); return 0; } void loop(deque &open, deque &closed,int range){ Situation a; int i = 0; while (!open.empty()){ cout << i++ << endl; if (open.front().code == GOAL){ cout << "成功:" << endl; a.showAnswer(closed); return; } if (open.empty()){ cout << "失败" << endl; return; } closed.push_back(open.front()); open.pop_front(); //节点n的深度是否等于深度界限 if (closed.back().deep == range){ //loop(open,closed,range);不能用递归 continue; } else{ //扩展节点n,把其后裔节点放入OPEN表的末端 Situation son1 = closed.back().up(); Situation son2 = closed.back().down(); Situation son3 = closed.back().left(); Situation son4 = closed.back().right(); /* 广度优先搜索和深度优先搜索的唯一区别就是子节点放到open表的位置: (1)广度优先搜索放到open表的后面 (2)深度优先搜索放到open表的前面 */ if (!son1.code.empty()){ if (!son1.isInOpen(open)&&!son1.isInClosed(closed)){ son1.father = closed.back().code; open.push_front(son1); } } if (!son2.code.empty()){ if (!son2.isInOpen(open) && !son2.isInClosed(closed)){ son2.father = closed.back().code; open.push_front(son2); } } if (!son3.code.empty()){ if (!son3.isInOpen(open) && !son3.isInClosed(closed)){ son3.father = closed.back().code; open.push_front(son3); } } if (!son4.code.empty()){ if (!son4.isInOpen(open) && !son4.isInClosed(closed)){ son4.father = closed.back().code; open.push_front(son4); } } //是否有任何后继节点为目标节点 if (son1.isGoal()){ cout << "后继节点中有目标节点:" << endl; son1.showAnswer(closed); break; } if (son2.isGoal()){ cout << "后继节点中有目标节点:" << endl; son2.showAnswer(closed); break; } if (son3.isGoal()){ cout << "后继节点中有目标节点:" << endl; son3.showAnswer(closed); break; } if (son4.isGoal()){ cout << "后继节点中有目标节点:" << endl; son4.showAnswer(closed); break; } } } }
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