Thread: Function causing error

Hi. I am having trouble with the search function in this program I am writing. I generate an infinite loop entering 2 at the command line, while entering 1 works fine. Any ideas why I'm running into a wall here? All ideas will be appreciated. Thanks. Steve

Code:

#include <iostream>
#include <vector>
#include <stack>
#include <string>

using namespace std;

template <class T>
struct State
{
    bool visited;
    vector<State*> children;
    T* data;

    State () : visited(false), data(0) { }
    virtual ~State () { }

    virtual void print (int indent = 0) = 0;
    virtual bool is_solution () = 0;
    virtual void generate_children () = 0;
};

template <class T>
bool search (State<T>& initial) //trouble with this fcn
{
    stack<State<T>*> s;
    State<T>* tmp;
    tmp=&initial;
    bool runner=true;
    while(runner)
    {
        if(tmp->is_solution())
        {
            tmp->print(2*s.size());
            cout<<"Solution found!\n";
            return true;
        }
        else
        {
            tmp->print(2*s.size());
            tmp->visited=true;
        }
        tmp->generate_children();
        int i;
        for(i=0; i<tmp->children.size(); i++)
        {
            cout<<"Going to child...\n";
            if(!tmp->children[i]->visited)
            {
                s.push(tmp);
                tmp=tmp->children[i];
                break;
            }
            if(tmp->children[i]->visited && s.empty())
            {
                cout<<"No solution exists!\n";
                return false;
            }
            else if(tmp->children[i]->visited && !s.empty())
            {
                tmp=s.top();
                s.pop();
                break;
            }
        }
    }
    
}

struct mt3data
{
    char ary[3][3];
};

struct mt3 : public State<mt3data>
{
    mt3 ();
    ~mt3 ();

    void print (int indent = 0);
    bool is_solution ();
    void generate_children ();

    void copy (const mt3& tocopy);
};

mt3::mt3 () {
    data = new mt3data;
    for (int i = 0; i < 3; ++i)
	for (int j = 0; j < 3; ++j)
	    data->ary[i][j] = '_';
}

mt3::~mt3 () { delete data; }

void mt3::print (int indent) {

    string theindent = "";
    for (int i = 0; i < indent; ++i)
	theindent += " ";

    for (int i = 0; i < 3; ++i) {
	cout << theindent;
	for (int j = 0; j < 3; ++j)
	    cout << data->ary[i][j];
	cout << endl;
    }
}

bool mt3::is_solution () {
    for (int i = 0; i < 3; ++i) {
	int rowcount = 0, colcount = 0;
	
	for (int j = 0; j < 3; ++j) {
	    if (data->ary[i][j] == 'X') ++rowcount;
	    if (data->ary[j][i] == 'X') ++colcount;
	}

	if (rowcount == 3 || colcount == 3) return true;
    }

    int left = 0, right = 0;
    for (int i = 0; i < 3; ++i) {
	if (data->ary[i][i] == 'X') ++left;
	if (data->ary[i][2-i] == 'X') ++right;
    }

    if (left == 3 || right == 3) return true;

    return false;
}

void mt3::generate_children() {

    if (!children.empty()) return;

    for (int i = 0; i < 3; ++i)
	for (int j = 0; j < 3; ++j)
	    if (data->ary[i][j] == '_') {
		mt3* tmp = new mt3;
		tmp->copy(*this);
		tmp->data->ary[i][j] = 'X';
		children.push_back(tmp);
	    }
}

void mt3::copy (const mt3& tocopy) {
    for (int i = 0; i < 3; ++i)
	for (int j = 0; j < 3; ++j)
	    data->ary[i][j] = tocopy.data->ary[i][j];
}

void syntax (string s) {
    cout << "Specify an integer argument as to which test to run: "
	 << endl
	 << "1. Successful MT3" << endl
	 << "2. Unsuccessful MT3" << endl;
    cout << endl;
    cout << "For example: " << s << " 2" << endl;
}


int main (int argc, char** argv) {
    if (argc == 1) {
	syntax(argv[0]);
	return 0;
    }

    string argument = argv[1];

    if (argument == "1") {
	mt3 goodmt3;
    
	goodmt3.data->ary[0][2] = '0';
	goodmt3.data->ary[1][2] = '0';
	goodmt3.data->ary[2][2] = '0';

	search(goodmt3);
	return 0;
    } else if (argument == "2") {
	mt3 badmt3;
	
	badmt3.data->ary[0][0] = '0';
	badmt3.data->ary[1][1] = '0';
	badmt3.data->ary[2][2] = '0';

	search(badmt3);
	return 0;
    }

    syntax(argv[0]);

    return 0;
}