棋盘覆盖问题（2.6）

这个问题自己一开始写的实现代码虽然和书上的在思想上是一样的，但是罗嗦了很多，因为对过程情况的划分不合理，导致冗余代码过多。书上：把问题分为四个子问题，分别覆盖四个子棋盘，然后在覆盖每一个子棋盘的时候再分为两种情况，即特殊方格是否在子棋盘中。而我的划分是：上来就以特殊方格的位置进行划分，那么代码就。。。

#include<iostream>
using namespace std;
const int SIZE = 100;
int cardNum=1;
int board[SIZE][SIZE];
//step既可以标志此时问题的规模，同时也可以将相对坐标转化为绝对坐标
void chessBoard(int step,int board_x,int board_y,int black_x,int black_y){
    if(step==2){
        int temp = board[black_x][black_y];
        board[board_x][board_y]=board[board_x+1][board_y]
        =board[board_x][board_y+1]=board[board_x+1][board_y+1]=cardNum;
        cardNum++;
        board[black_x][black_y]=temp;//还原回来
        return;
    }
    //计算中线的绝对坐标
    int mid_x=board_x+step/2;
    int mid_y=board_y+step/2;

    //黑快在左上角的情形
    if(black_x<mid_x&&black_y<mid_y){
        board[mid_x][mid_y]=board[mid_x-1][mid_y]=board[mid_x][mid_y-1]=cardNum;
        cardNum++;
        chessBoard(step/2,board_x,board_y,black_x,black_y);
        chessBoard(step/2,mid_x,board_y,mid_x,mid_y-1);
        chessBoard(step/2,board_x,mid_y,mid_x-1,mid_y);
        chessBoard(step/2,mid_x,mid_y,mid_x,mid_y);
        return ;
    }
    //黑快在右上的情形
    if(black_x>=mid_x&&black_y<mid_y){
        board[mid_x][mid_y]=board[mid_x-1][mid_y-1]=board[mid_x-1][mid_y]=cardNum;
        cardNum++;
        chessBoard(step/2,board_x,board_y,mid_x-1,mid_y-1);
        chessBoard(step/2,mid_x,board_y,black_x,black_y);
        chessBoard(step/2,board_x,mid_y,mid_x-1,mid_y);
        chessBoard(step/2,mid_x,mid_y,mid_x,mid_y);
        return;
    }
    //左下的情形
    if(black_x<mid_x&&black_y>=mid_y){
        board[mid_x][mid_y]=board[mid_x-1][mid_y-1]=board[mid_x][mid_y-1]=cardNum;
        cardNum++;
        chessBoard(step/2,board_x,board_y,mid_x-1,mid_y-1);
        chessBoard(step/2,mid_x,board_y,mid_x,mid_y-1);
        chessBoard(step/2,board_x,mid_y,black_x,black_y);
        chessBoard(step/2,mid_x,mid_y,mid_x,mid_y);
        return;
    }
    //右下的情形
    if(black_x>=mid_x&&black_y>=mid_y){
        board[mid_x-1][mid_y-1]=board[mid_x-1][mid_y]=board[mid_x][mid_y-1]=cardNum;
        cardNum++;
        chessBoard(step/2,board_x,board_y,mid_x-1,mid_y-1);
        chessBoard(step/2,mid_x,board_y,mid_x,mid_y-1);
        chessBoard(step/2,board_x,mid_y,mid_x-1,mid_y);
        chessBoard(step/2,mid_x,mid_y,black_x,black_y);
        return;
    }
}
int main(){
    int step;
    cin>>step;
    int x,y;
    cin>>x>>y;
    chessBoard(step,0,0,x,y);
    for(int i=0;i<step;i++){
        for(int j=0;j<step;j++)
            cout<<board[i][j]<<" ";
        cout<<endl;
    }
    return 0;
}