Playing Chess

Time Limit: 1000ms, Special Time Limit:2500ms, Memory Limit:32768KB

Total submit users: 18, Accepted users: 18

Problem 10763 : No special judgement

Problem description

yiyi and birdman like to play chess.They sometimes play chess in QQ game. They discovered that the game cost a lot of time. They have lots of things to do, for instance doing homework, programming.So they come up with a good game, this game is played on the chessboard too, Is a 4 × 3 Lattice. However, only a pawn - horse. The horse on the chessboard of arbitrary position ,The pawn returns to the original location of a number of different routes ,(if a position has been arrived then should not go again and the horse takes ‘日’ route), They have to give a total number of different routes and the faster is the winner. Because they are very good at programming , Through programming they can easily give the answer. This new game is not a challenge to them ,But it maybe a challenge to you. Your task now is to work out a procedure to tell us the answer ,can you win one of them?

Input

The input consists of some test cases. Each input a lines. Each line consists of two integer, StarX <= 3 and StarY <= 4 (the original position of the horse on the chessboard).End of EOF.

Output

For each input set, output integer N,the total number of different routes the horse can return to the original position .If the position is not satisfied with the above conditions of the intput ,output “Error !”

Sample Input

0 -1 0 0 0 1

Sample Output

Error ! 1508 3457

Judge Tips

The routes of picture (1) is right, but (2) is wrong, because (2,1) arrived tiwice .

Problem Source

/// 用递归就是了，//// 水题充数

#include <iostream>
using namespace std;
int sum,starx,stary;
bool chess[5][4];

void get(int x, int y);
void deal(int x, int y){
    if(x==starx && y==stary)
        sum++;
    else if(!chess[y][x]){
        chess[y][x] = true;
        get(x,y);
        chess[y][x] = false;
    }
}

void get(int x, int y){
    if(x+2<=3){
        if(y+1<=4)
            deal(x+2,y+1);
        if(y-1>=0)
            deal(x+2,y-1);
    }
    if(x-2>=0){
        if(y+1<=4)
            deal(x-2,y+1);
        if(y-1>=0)
            deal(x-2,y-1);
    }
    if(y+2<=4){
        if(x+1<=3)
            deal(x+1,y+2);
        if(x-1>=0)
            deal(x-1,y+2);
    }
    if(y-2>=0){
        if(x+1<=3)
            deal(x+1,y-2);
        if(x-1>=0)
            deal(x-1,y-2);
    }
}

int main(){
    for(; cin>>starx>>stary; ){
        if(starx<0 || starx>3 || stary<0 || stary>4)
            cout<<"Error !"<<endl;
        else{
            sum = 0;
            get(starx,stary);
            cout<<sum<<endl;
        }
    }
    return 0;
}

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