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  1.  
  2. #include <stdio.h>
  3. #include <stdlib.h>
  4. #include <limits.h>
  5. #include <inttypes.h>
  6.  
  7. uint32_t multiply (uint16_t a, uint16_t b)
  8. {
  9.   return ((a &  ( (int16_t)( ( b & (1 << 0) ) << 15 ) ) / ( 1 << 15) ) << 0 ) +
  10.          ((a &  ( (int16_t)( ( b & (1 << 1) ) << 14 ) ) / ( 1 << 15) ) << 1 ) +
  11.          ((a &  ( (int16_t)( ( b & (1 << 2) ) << 13 ) ) / ( 1 << 15) ) << 2 ) +
  12.          ((a &  ( (int16_t)( ( b & (1 << 3) ) << 12 ) ) / ( 1 << 15) ) << 3 ) +
  13.          ((a &  ( (int16_t)( ( b & (1 << 4) ) << 11 ) ) / ( 1 << 15) ) << 4 ) +
  14.          ((a &  ( (int16_t)( ( b & (1 << 5) ) << 10 ) ) / ( 1 << 15) ) << 5 ) +
  15.          ((a &  ( (int16_t)( ( b & (1 << 6) ) << 9  ) ) / ( 1 << 15) ) << 6 ) +
  16.          ((a &  ( (int16_t)( ( b & (1 << 7) ) << 8  ) ) / ( 1 << 15) ) << 7 ) +
  17.          ((a &  ( (int16_t)( ( b & (1 << 8) ) << 7  ) ) / ( 1 << 15) ) << 8 ) +
  18.          ((a &  ( (int16_t)( ( b & (1 << 9) ) << 6  ) ) / ( 1 << 15) ) << 9 ) +
  19.          ((a &  ( (int16_t)( ( b & (1 <<10) ) << 5  ) ) / ( 1 << 15) ) << 10) +
  20.          ((a &  ( (int16_t)( ( b & (1 <<11) ) << 4  ) ) / ( 1 << 15) ) << 11) +
  21.          ((a &  ( (int16_t)( ( b & (1 <<12) ) << 3  ) ) / ( 1 << 15) ) << 12) +
  22.          ((a &  ( (int16_t)( ( b & (1 <<13) ) << 2  ) ) / ( 1 << 15) ) << 13) +
  23.          ((a &  ( (int16_t)( ( b & (1 <<14) ) << 1  ) ) / ( 1 << 15) ) << 14) +
  24.          ((a &  ( (int16_t)( ( b & (1 <<15) ) << 0  ) ) / ( 1 << 15) ) << 15);
  25. }
  26.  
  27. int main(void)
  28. {
  29.  
  30.   uint16_t a, b;
  31.   a = 0;
  32.   b = 0;
  33.  
  34.   do
  35.   {
  36.     if (multiply(a, b) != a * b)
  37.  
  38.  
  39.       fprintf(stderr,
  40.                "ERROR:\n"
  41.                "my: %u\n"
  42.                "norm: %u\n"
  43.                "%hu * %hu\n"
  44.                "\n",
  45.                multiply(a, b), (a * b),a, b
  46.              );
  47.  
  48.     if (UINT16_MAX == a)
  49.     {
  50.       b++;
  51.     }
  52.     a++;
  53.   //fprintf(stderr, "%hu * %hu\n", a, b);
  54.   } while ( ( a != 0 ) || (b != 0) );
  55.  
  56.   fprintf(stderr, "%"PRIu16"* ""%"PRIu16"\n", a, b);
  57.   printf("Done!\n");
  58.  
  59.   return 0;
  60. }
  61.  
Time limit exceeded #stdin #stdout 5s 1784KB
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https://ideone.com/FSG1Zn
language:
C (gcc 8.3)
created:
10 years ago
visibility:
public

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