分治法-棋盘覆盖问题 C++代码实现

#include<iostream>
#include<algorithm>
#include<cstdio>
#include<cstring>
#include<vector>
#include<queue>
#define LL long long
using namespace std;
int num;
int grid[100][100];
inline bool judge(int sx,int sy,int size,int dx,int dy)
{
    return (sx<=dx&&dx<=sx+size-1)&&(sy<=dy&&dy<=sy+size-1);
}
void dfs(int sx,int sy,int size,int dx,int dy)
{
    if(size==1) return;
    int len=size/2;
    int s;
    //左上右上左下右下分别是1234
    if(judge(sx,sy,len,dx,dy)) s=1;
    else if(judge(sx,sy+len,len,dx,dy)) s=2;
    else if(judge(sx+len,sy,len,dx,dy)) s=3;
    else if(judge(sx+len,sy+len,len,dx,dy)) s=4;
    int ex=sx+len,ey=sy+len;
    int c=++num;
    if(s!=1)
    {
        grid[ex-1][ey-1]=c;
        dfs(sx,sy,len,ex-1,ey-1);
    }
    else
        dfs(sx,sy,len,dx,dy);
    if(s!=2)
    {
        grid[ex-1][ey]=c;
        dfs(sx,sy+len,len,ex-1,ey);
    }
    else
        dfs(sx,sy+len,len,dx,dy);
    if(s!=3)
    {
        grid[ex][ey-1]=c;
        dfs(sx+len,sy,len,ex,ey-1);
    }
    else
        dfs(sx+len,sy,len,dx,dy);
    if(s!=4)
    {
        grid[ex][ey]=c;
        dfs(sx+len,sy+len,len,ex,ey);
    }
    else
        dfs(sx+len,sy+len,len,dx,dy);
}
int main()
{
    int n,dx,dy;
    //输入棋盘的边长，要求n是2的幂；再输入空白格子的坐标。棋盘左上角是（1，1）
    while(scanf("%d%d%d",&n,&dx,&dy)!=EOF)
    {
        memset(grid,0,sizeof(grid));
        grid[dx][dy]=-1;
        num=0;
        dfs(1,1,n,dx,dy);
        for(int i=1; i<=n; ++i)
        {
            for(int j=1; j<=n; ++j)
                printf("%3d ",grid[i][j]);
            printf("\n");
        }
    }
    return 0;
}