八數(shù)碼問(wèn)題求解（1）深度優(yōu)先搜索

jayce 發(fā)布于2019-06-26 18:12 / 2961人閱讀

摘要：老師讓用中方式都實(shí)現(xiàn)一遍，分別是廣度優(yōu)先搜索深度優(yōu)先搜索和啟發(fā)式搜索。先分享深度優(yōu)先搜索，后兩篇我會(huì)分享廣度優(yōu)先搜索和啟發(fā)式搜索的實(shí)現(xiàn)。

人工智能課，第一個(gè)實(shí)驗(yàn)就是八數(shù)碼問(wèn)題。老師讓用3中方式都實(shí)現(xiàn)一遍，分別是廣度優(yōu)先搜索、深度優(yōu)先搜索和啟發(fā)式搜索。心塞╮(╯▽╰)╭。緊急補(bǔ)了一些數(shù)據(jù)結(jié)構(gòu)的知識(shí)，就匆匆上陣。先分享深度優(yōu)先搜索，后兩篇我會(huì)分享廣度優(yōu)先搜索和啟發(fā)式搜索的實(shí)現(xiàn)。

概念就不講了，百度就行了。簡(jiǎn)單說(shuō)一下我的實(shí)現(xiàn)：Situation類(lèi)存儲(chǔ)節(jié)點(diǎn)信息，包括父節(jié)點(diǎn)的code值（code是一個(gè)字符串，存儲(chǔ)的是八數(shù)碼的狀態(tài)，比如“138427056”），當(dāng)前節(jié)點(diǎn)的code值，以及深度（深度從0開(kāi)始，即起始節(jié)點(diǎn)深度為0）；在Test.cpp的main函數(shù)中，我定義了兩個(gè)鏈表open和closed分別存放未被擴(kuò)展的節(jié)點(diǎn)和被擴(kuò)展的節(jié)點(diǎn)。深度優(yōu)先，新生成的有效的子節(jié)點(diǎn)存放在open表的開(kāi)頭。每次擴(kuò)展，拿open表的開(kāi)頭的那個(gè)節(jié)點(diǎn)來(lái)擴(kuò)展，方法是把open表的頭節(jié)點(diǎn)移動(dòng)到closed表的末端，生成的最多4個(gè)有效的子節(jié)點(diǎn)存放在open表的開(kāi)頭。其他就是比較生成的節(jié)點(diǎn)和目標(biāo)節(jié)點(diǎn)是否相等了。

以下代碼在win8.1下VS2013中測(cè)試成功。

頭文件Deep.h：

#include
#include"queue"
#include"string"
#include

using namespace std;

const string GOAL = "803214765";

class Situation{
private:
    
public:
    string father;
    string code;//當(dāng)前狀態(tài)
    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);//顯示解答
    Situation() :father(""), code(""), deep(-1){};
};

Deep.cpp：

#include"Deep.h"

Situation Situation::up(){
    string::size_type loc = code.find("0");//0的位置,從0開(kāi)始計(jì)數(shù)
    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,從0開(kāi)始計(jì)數(shù)
    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,從0開(kāi)始計(jì)數(shù)
    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,從0開(kāi)始計(jì)數(shù)
    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();
    }
}

//路徑
deque Situation::showWay(deque &closed){
    //cout << closed.size() << endl;
    deque dequeList;
    Situation temp = closed.back();
    dequeList.push_back(temp);

    //closed表從后往前，根據(jù)father值找到路徑
    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();
    }
    //輸出目標(biāo)
    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存放未擴(kuò)展節(jié)點(diǎn)，closed存放已擴(kuò)展節(jié)點(diǎn)
    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 << "失敗" << endl;
            return;
        }
        closed.push_back(open.front());
        open.pop_front();
        //節(jié)點(diǎn)n的深度是否等于深度界限
        if (closed.back().deep == range){
            //loop(open,closed,range);不能用遞歸
            continue; 
        }
        else{
            //擴(kuò)展節(jié)點(diǎn)n,把其后裔節(jié)點(diǎn)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();
            /*
            廣度優(yōu)先搜索和深度優(yōu)先搜索的唯一區(qū)別就是子節(jié)點(diǎn)放到open表的位置：
            （1）廣度優(yōu)先搜索放到open表的后面
            （2）深度優(yōu)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);
                }
                
            }
            //是否有任何后繼節(jié)點(diǎn)為目標(biāo)節(jié)點(diǎn)
            if (son1.isGoal()){
                cout << "后繼節(jié)點(diǎn)中有目標(biāo)節(jié)點(diǎn)：" << endl;
                son1.showAnswer(closed);
                break;
            }
            if (son2.isGoal()){
                cout << "后繼節(jié)點(diǎn)中有目標(biāo)節(jié)點(diǎn)：" << endl;
                son2.showAnswer(closed);
                break;
            }
            if (son3.isGoal()){
                cout << "后繼節(jié)點(diǎn)中有目標(biāo)節(jié)點(diǎn)：" << endl;
                son3.showAnswer(closed);
                break;
            }
            if (son4.isGoal()){
                cout << "后繼節(jié)點(diǎn)中有目標(biāo)節(jié)點(diǎn)：" << endl;
                son4.showAnswer(closed);
                break;
            }
        }
    }
}