蓝桥杯 2014真题 打印图形

标题：打印图形

    小明在X星球的城堡中发现了如下图形和文字：
rank=3
   *
  * *
 *   *  
* * * *

rank=5
               *                                                      
              * *                                                     
             *   *                                                    
            * * * *                                                   
           *       *                                                  
          * *     * *                                                 
         *   *   *   *                                                
        * * * * * * * *                                               
       *               *                                              
      * *             * *                                             
     *   *           *   *                                            
    * * * *         * * * *                                           
   *       *       *       *  
  * *     * *     * *     * *  
 *   *   *   *   *   *   *   *
* * * * * * * * * * * * * * * *  

ran=6
                               *                                      
                              * *                                     
                             *   *                                    
                            * * * *                                   
                           *       *                                  
                          * *     * *                                 
                         *   *   *   *                                
                        * * * * * * * *                               
                       *               *                              
                      * *             * *                             
                     *   *           *   *                            
                    * * * *         * * * *                           
                   *       *       *       *                          
                  * *     * *     * *     * *                         
                 *   *   *   *   *   *   *   *                        
                * * * * * * * * * * * * * * * *                       
               *                               *                      
              * *                             * *                     
             *   *                           *   *                    
            * * * *                         * * * *                   
           *       *                       *       *                  
          * *     * *                     * *     * *                 
         *   *   *   *                   *   *   *   *                
        * * * * * * * *                 * * * * * * * *               
       *               *               *               *              
      * *             * *             * *             * *             
     *   *           *   *           *   *           *   *            
    * * * *         * * * *         * * * *         * * * *           
   *       *       *       *       *       *       *       *          
  * *     * *     * *     * *     * *     * *     * *     * *         
 *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *        
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *       
                                                                      

    小明开动脑筋，编写了如下的程序，实现该图形的打印。

#define N 70

void f(char a[][N], int rank, int row, int col)
{
	if(rank==1){
		a[row][col] = '*';
		return;
	}
	
	int w = 1;
	int i;
	for(i=0; i<rank-1; i++) w *= 2;
	
	____________________________________________;
	f(a, rank-1, row+w/2, col);
	f(a, rank-1, row+w/2, col+w);
}

int main()
{
	char a[N][N];
	int i,j;
	for(i=0;i<N;i++)
	for(j=0;j<N;j++) a[i][j] = ' ';
	
	f(a,6,0,0);
	
	for(i=0; i<N; i++){
		for(j=0; j<N; j++) printf("%c",a[i][j]);
		printf("\n");
	}
	
	return 0;
}

答案：

f(a,rank-1,row,col+w/2);

先大致了解题目含义，基本能看懂代码。多试几次结果就出来了，可以先从rank=3可以试。