A Knight's Journey(P2488)

一道比较简单的搜索题，自己也是一次过，过得比较爽。哈哈。。

#include<iostream>#include<stdlib.h>#include<math.h>#include<stdio.h>#include<algorithm>#include<queue>#include<string.h>#include<stack>#include<math.h>#include<stdlib.h>#include<list>#include<vector>using namespace std;int fang[8][2]={{-2,-1},{-2,1},{-1,-2},{-1,2},{1,-2},{1,2},{2,-1},{2,1}};int lie,heng;bool a[100][100];char go[100]="aABCDEFGHIJKLMNOPQRSTUVWXYZ";int ans;int xx[100],yy[199];int lx,ly;bool in (int i,int j){    if (i<1||i>lie)        return false;    if (j<1||j>heng)        return false;    return true;}bool dfs(int i,int j){//    cout<<i<<' '<<j<<endl;    int k;    if (ans==lie*heng)    {        return false;    }    bool f=true;;    for (k=0;k<8;k++)    {        int x=fang[k][0]+i;        int y=fang[k][1]+j;        if (in(x,y)&&!a[x][y])        {            a[x][y]=true;            xx[ans]=x;            yy[ans]=y;            ans++;            f= dfs(x,y);            if (!f)            {                break;            }            ans--;            a[x][y]=false;        }    }    return f;}int main(){    int i,j,k;    int t;    cin>>t;    int num=0;    while (t--)    {        lx=0;        ly=0;        num++;        ans=1;        cin>>heng>>lie;        memset(a,false,sizeof(a));        a[1][1]=true;                cout<<"Scenario #"<<num<<':'<<endl;        if (dfs(1,1) )        {            //cout<<ans<<endl;            cout<<"impossible"<<endl<<endl;            continue;        }        xx[0]=1;        yy[0]=1;        for (i=0;i<lie*heng;i++)            cout<<go[xx[i]]<<yy[i];        cout<<endl<<endl;                }}

A Knight's Journey

Time Limit: 1000MS Memory Limit: 65536KTotal Submissions: 18979 Accepted: 6377

Description

Background
The knight is getting bored of seeing the same black and white squares again and again and has decided to make a journey
around the world. Whenever a knight moves, it is two squares in one direction and one square perpendicular to this. The world of a knight is the chessboard he is living on. Our knight lives on a chessboard that has a smaller area than a regular 8 * 8 board, but it is still rectangular. Can you help this adventurous knight to make travel plans?

Problem
Find a path such that the knight visits every square once. The knight can start and end on any square of the board.

Input

The input begins with a positive integer n in the first line. The following lines contain n test cases. Each test case consists of a single line with two positive integers p and q, such that 1 <= p * q <= 26. This represents a p * q chessboard, where p describes how many different square numbers 1, . . . , p exist, q describes how many different square letters exist. These are the first q letters of the Latin alphabet: A, . . .

Output

The output for every scenario begins with a line containing "Scenario #i:", where i is the number of the scenario starting at 1. Then print a single line containing the lexicographically first path that visits all squares of the chessboard with knight moves followed by an empty line. The path should be given on a single line by concatenating the names of the visited squares. Each square name consists of a capital letter followed by a number.
If no such path exist, you should output impossible on a single line.

Sample Input

31 12 34 3

Sample Output

Scenario #1:A1Scenario #2:impossibleScenario #3:A1B3C1A2B4C2A3B1C3A4B2C4

Source

TUD Programming Contest 2005, Darmstadt, Germany