text: /* Find the unique positive integer 
   * whose square has the form
   * 1_2_3_4_5_6_7_8_9_0,
   * where each "_" is a single digit.
   * Project Euler: 206 
   * Answer: 1389019170 */
  
  /* While this is done, it takes about a minute
   * fourty. Develop more efficient algorithm */
  
  
  /* Includes */
  #include <stdio.h>
  #include <stdlib.h>
  #include <stdint.h>
  #include <inttypes.h>
  
  
  /* Definitions */
  #define MAX_LEN 20
  #define MIN     1020304050607080900 
  
  
  /* Prototypes */
  int isConcealedSquare(uint64_t i);
  int main(int argc, char** argv);
  
  
  int main(int argc, char** argv)
  {
          (void) argc;
          (void) argv;
  
          uint64_t test; uint64_t i;
  
          for(i = 0; ; i+= 2){
  
                  test = i*i;
  
                  if(test < MIN) continue;
  
                  if(isConcealedSquare(test)) break;
  
          }
          
          printf("%"PRIu64"\n", i);
  
  	return 0;
  
  }
  
  
  int isConcealedSquare(uint64_t i)
  {
          if(i % 10 != 0) return 0;
          i /= 100;
  
          for(uint32_t a = 9; i; a--){
                  if(i % 10 != a) return 0;
                  i /= 100;
          }
  
          return 1;
  
  }
  
  