在简单的 Rush Hour 求解器中使用 BFS - 为啥我的代码不能求解电路板？

Posted 2023-02-21

【中文标题】在简单的 Rush Hour 求解器中使用 BFS - 为啥我的代码不能求解电路板？

【英文标题】：Using BFS in a simple Rush Hour solver - why is my code not solving the board?在简单的 Rush Hour 求解器中使用 BFS - 为什么我的代码不能求解电路板？

【发布时间】：2012-12-09 18:37:18

【问题描述】：

更新 - 主要问题已由下面的回复者解决（我有一个 '=' 我应该有一个 '=='），但现在我得到了错误的输出。我想我会按照建议提供一些输入/输出示例，这样也许有人可以发现我哪里出错了。

假设我输入了输入：

......

......

xx....

......

......

......

这应该会产生输出：

4

x r

x r

x r

x r

表示 x 在 4 步中到达了第 3 行最右边的位置，并且 x 必须每步向右移动。

相反，我得到了输出：

3

x r

x l

x r

在下面的代码中，程序接受一个 6x6 的字符块来表示游戏板。 （句号是空格，字符代表汽车。）在板类和主要功能中完成的工作是正确的，因为我已经与我的教授核实过。但是，我正在尝试纠正我的输出。我知道我在求解函数中使用的逻辑并不是解决此问题的最佳方法，但我必须尝试让它发挥作用，这样我就可以在不复制教授的解决方案的情况下拿回分数。

#include <iostream>
#include <string>
#include <queue>
#include <set>
#include <list>

using namespace std;

class board

public:
board() count = 0;

bool isSolved()

    return currState[17] = 'x';


string currState;
string moveList;
int count;
;

bool operator < (const board& board1, const board& board2)

return board1.currState < board2.currState;


void solve (const board& curr, int i, list<board>& toTest, const set<board>& testedSet, bool vert)

board newMove(curr);

if (vert == false)

if (i % 6 == 0 && curr.currState[i] != '.')

    if (curr.currState[i] == curr.currState[i+1] && curr.currState[i+2] == '.')
    
        newMove.moveList = newMove.moveList + newMove.currState[i] + " " + "r" + "\n";
        newMove.currState[i+2] = newMove.currState[i];
        newMove.currState[i] = '.';
        newMove.count++;
    

    if (curr.currState[i] == curr.currState[i+1] && curr.currState[i] == curr.currState[i+2] && curr.currState[i+3] == '.')
    
        newMove.moveList = newMove.moveList + newMove.currState[i] + " " + "r" + "\n";
        newMove.currState[i+3] = newMove.currState[i];
        newMove.currState[i] = '.';     
        newMove.count++;
    


else if ((i + 1) % 6 == 0 && curr.currState[i] != '.')

    if (curr.currState[i] == curr.currState[i-1] && curr.currState[i-2] == '.')
    
        newMove.moveList = newMove.moveList + newMove.currState[i] + " " + "l" + "\n";
        newMove.currState[i-2] = newMove.currState[i];
        newMove.currState[i] = '.';
        newMove.count++;
    

    if (curr.currState[i] == curr.currState[i-1] && curr.currState[i] == curr.currState[i-2] && curr.currState[i-3] == '.')
    
        newMove.moveList = newMove.moveList + newMove.currState[i] + " " + "l" + "\n";
        newMove.currState[i-3] = newMove.currState[i];
        newMove.currState[i] = '.';
        newMove.count++;
    


else

    if (i % 2 != 0 && i % 3 != 0 && curr.currState[i] != '.')
    
        if (curr.currState[i] == curr.currState[i+1] && curr.currState[i-1] == '.' && curr.currState[i+2] != curr.currState[i])
        
            newMove.moveList = newMove.moveList + newMove.currState[i] + " " + "l" + "\n";
            newMove.currState[i-1] = newMove.currState[i];
            newMove.currState[i+1] = '.';
            newMove.count++;
        

        if (curr.currState[i] == curr.currState[i+1] && curr.currState[i+2] == '.' && curr.currState[i-1] != curr.currState[i])
        
            newMove.moveList = newMove.moveList + newMove.currState[i] + " " + "r" + "\n";
            newMove.currState[i+2] = newMove.currState[i];
            newMove.currState[i] = '.';
            newMove.count++;
        

        if (curr.currState[i] == curr.currState[i+1] && curr.currState[i] == curr.currState[i+2] && curr.currState[i-1] == '.' && curr.currState[i+3] != curr.currState[i])
        
            newMove.moveList = newMove.moveList + newMove.currState[i] + " " + "l" + "\n";
            newMove.currState[i-1] = newMove.currState[i];
            newMove.currState[i+2] = '.';
            newMove.count++;
        

        if (curr.currState[i] == curr.currState[i+1] && curr.currState[i] == curr.currState[i+2] && curr.currState[i+3] == '.' && curr.currState[i-1] != curr.currState[i])
        
            newMove.moveList = newMove.moveList + newMove.currState[i] + " " + "r" + "\n";
            newMove.currState[i+3] = newMove.currState[i];
            newMove.currState[i] = '.';
            newMove.count++;
        
    

    if (i % 2 == 0 && (i + 2) % 6 != 0 && curr.currState[i] != '.')
    

        if (curr.currState[i] == curr.currState[i+1] && curr.currState[i-1] == '.' && curr.currState[i+2] != curr.currState[i])
        
            newMove.moveList = newMove.moveList + newMove.currState[i] + " " + "l" + "\n";
            newMove.currState[i-1] = newMove.currState[i];
            newMove.currState[i+1] = '.';
            newMove.count++;
        

        if (curr.currState[i] == curr.currState[i+1] && curr.currState[i+2] == '.' && curr.currState[i-1] != curr.currState[i])
        
            newMove.moveList = newMove.moveList + newMove.currState[i] + " " + "r" + "\n";
            newMove.currState[i+2] = newMove.currState[i];
            newMove.currState[i] = '.';
            newMove.count++;
        

        if (curr.currState[i] == curr.currState[i+1] && curr.currState[i] == curr.currState[i+2] && curr.currState[i+3] == '.' && curr.currState[i-1] != curr.currState[i])
        
            newMove.moveList = newMove.moveList + newMove.currState[i] + " " + "r" + "\n";
            newMove.currState[i+3] = newMove.currState[i];
            newMove.currState[i] = '.';
            newMove.count++;
        
    

    if (i % 3 == 0 && curr.currState[i] != '.')
    
        if (curr.currState[i] == curr.currState[i+1] && curr.currState[i-1] == '.' && curr.currState[i+2] != curr.currState[i])
        
            newMove.moveList = newMove.moveList + newMove.currState[i] + " " + "l" + "\n";
            newMove.currState[i-1] = newMove.currState[i];
            newMove.currState[i+1] = '.';
            newMove.count++;
        

        if (curr.currState[i] == curr.currState[i+1] && curr.currState[i+2] == '.' && curr.currState[i-1] != curr.currState[i])
        
            newMove.moveList = newMove.moveList + newMove.currState[i] + " " + "r" + "\n";
            newMove.currState[i+2] = newMove.currState[i];
            newMove.currState[i] = '.';
            newMove.count++;
        
    



if (vert == true)

    if (i < 17)
    
        if (curr.currState[i] == curr.currState[i+6] && curr.currState[i] == curr.currState[i+12] && curr.currState[i+18] == '.')
        
            newMove.moveList = newMove.moveList + newMove.currState[i] + " " + "d" + "\n";
            newMove.currState[i+18] = newMove.currState[i];
            newMove.currState[i] = '.';
            newMove.count++;
        

        if (curr.currState[i] == curr.currState[i+6] && curr.currState[i+12] == '.')
        
            if (i < 6 || curr.currState[i] != curr.currState[i-6])
            
                newMove.moveList = newMove.moveList + newMove.currState[i] + " " + "d" + "\n";
                newMove.currState[i+12] = newMove.currState[i];
                newMove.currState[i] = '.';
                newMove.count++;
            
        
    

    if (i > 17)
    
        if (curr.currState[i] == curr.currState[i-6] && curr.currState[i] == curr.currState[i-12] && curr.currState[i-18] == '.')
        
            newMove.moveList = newMove.moveList + newMove.currState[i] + " " + "u" + "\n";
            newMove.currState[i-18] = newMove.currState[i];
            newMove.currState[i] = '.';
            newMove.count++;
        

        if (curr.currState[i] == curr.currState[i-6] && curr.currState[i-12] == '.')
        
            if (i > 29 || curr.currState[i] != curr.currState[i+6])
            
                newMove.moveList = newMove.moveList + newMove.currState[i] + " " + "u" + "\n";
                newMove.currState[i-12] = newMove.currState[i];
                newMove.currState[i] = '.';
                newMove.count++;
            
        
    





if (testedSet.find(newMove) == testedSet.end())
    toTest.push_back(newMove);


int main()

list<board> toBeTested;
string input;
board current;
set<board> tested;
bool vertical = false;

for (int i = 0; i < 6; i++)

    getline(cin, input);
    current.currState += input;


toBeTested.push_back(current);

while (toBeTested.size() > 0 && current.isSolved() == false)

    current = toBeTested.front();
    toBeTested.pop_front();

    if (current.isSolved() == false && tested.find(current) == tested.end())
    
        tested.insert(current);

        for (int i = 0; i < 36; i++)
        
            solve(current, i, toBeTested, tested, vertical);
            vertical = true;
            solve(current, i, toBeTested, tested, vertical);
            vertical = false;
        

    


if (current.isSolved() == false)
    cout << current.count << endl << current.moveList;
else
    cout << -1 << endl;

return 0;

【问题讨论】：

return currState[17] = 'x'; 应该是return currState[17] == 'x';

如果您能提供一些示例输入和输出将会有所帮助。

好的。是的。这帮助很大。哈哈。不敢相信我是个大白痴，但我想有人发现这样的错误总是有帮助的。谢谢你。当然，这解决了 -1 问题，但现在我得到了错误的答案。例如，当我进入第三行前面只有两个 x 的网格时，输出应为“4”（需要 4 步才能将 x 移到点 17）和“x r x r x r x r”。相反，它读取 3 个动作，并且 "x r x l x r"

【参考方案1】：

在这里很难弄清楚您要做什么，因为许多值是硬编码的，并且程序中没有使用很多抽象。

我猜你正在尝试做类似http://www.theiling.de/projects/rushhour.html 的事情，其中​​输入是一个类似的板：

aaobcc ..ob.. xx... deeffp d..k.p hh.k.p

如果您从我的评论中更正board::isSolved()：

bool isSolved()

    return currState[17] == 'x';

你至少会得到-1以外的东西：

10 b d cl 小时 普 普 普 fr 库 升 小时

但是，这并不能解决输入问题。

您似乎没有正确计算下一个状态。移动车辆后，应该有一个循环遍历车辆的每一部分。

一定要尝试抽象更多细节。例如，也许您可​​以向board 添加方法，用于（1）计算有效移动列表和（2）应用单个移动，返回一个新的board。此外，如果您还没有学会如何使用诸如gdb 之类的调试器，那么现在是开始学习的好时机。见How do I use the MinGW gdb debugger to debug a C++ program in Windows?

【讨论】：

你是对的，我为草率的代码道歉。我想我会跟踪求解函数，看看我哪里出错了。谢谢你的好建议。

@TheRationalist：顺便说一下，BerkeleyX（edX 的一部分）有一个关于人工智能的优秀免费课程：CS188.1x: Artificial Intelligence。课程已结束，但您仍然可以注册并学习材料。第一周是搜索算法 BFS、DFS、统一成本和 A*。如果你完成了第一个编程项目，你会看到一个很好的例子，可以抽象出搜索问题中的细节。