poj 2488

#include<iostream>
#include <vector>
#include<string> 
using namespace std;

int n, p, q, total;
int area[26][26];
int dirX[8] = {-1, 1, -2, 2, -2, 2, -1, 1};
int dirY[8] = {-2, -2, -1, -1, 1, 1, 2, 2};
vector<int> orderX;
vector<int> orderY; 
int dfs(int x, int y, int sum)
{
    //Èç¹ûÊÇ×îºóÒ»¸öÇÒÒѾ­³É¹¦; 
    if(sum == total)
    {
        orderX.push_back(x);
        orderY.push_back(y);
        return 1;
    }
    
    area[x][y] = 1;
    int res = 0;
    for(int i = 0; i < 8; ++i)
    {
            int nx = x+dirX[i];
            int ny = y+dirY[i];
            if(nx >= 0 && nx < p && ny >= 0 && ny < q && area[nx][ny] == -1)
            {
                int temp = sum+1;
                res = dfs(nx, ny, temp);
                if(res)
                {
                    orderX.push_back(x);
                    orderY.push_back(y);
                    break;
                }
            }
    }
    if(!res)
        area[x][y] = -1;
    return res;
}

void solver(int no)
{
    memset(area, -1, sizeof(int)*676);
    cout << "Scenario #"<< no <<":" << endl;
    orderX.clear();
    orderY.clear();
    if(dfs(0, 0, 1))
    {
        
        for(int i = orderX.size()-1; i >= 0; --i)
        {
            char c = 65 + orderY[i];
            cout << c << orderX[i]+1;
        }
    }
    else
    {
        cout << "impossible";
    }
        cout << endl << endl;;
}

int main()
{
    cin >> n;
    for(int i = 0; i < n; ++i)
    {
        cin >> p >> q;
        total = p * q;
        solver(i+1);
    }    
    return 0;
}