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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <limits.h>
  4. #include <inttypes.h>
  5.  
  6. uint32_t multiply (uint16_t a, uint16_t b)
  7. {
  8.   register uint32_t result = 0;
  9.   char n = 0, n2 = 15;
  10.  
  11.     result += (a &  ( (int16_t)( ( b & (1 << n) ) << n2 ) ) / ( 1 << 15) ) << n;  
  12.   n++; n2--;
  13.  
  14.     result += (a &  ( (int16_t)( ( b & (1 << n) ) << n2 ) ) / ( 1 << 15) ) << n;  
  15.   n++; n2--;
  16.  
  17.     result += (a &  ( (int16_t)( ( b & (1 << n) ) << n2 ) ) / ( 1 << 15) ) << n;  
  18.   n++; n2--;
  19.  
  20.     result += (a &  ( (int16_t)( ( b & (1 << n) ) << n2 ) ) / ( 1 << 15) ) << n;  
  21.   n++; n2--;
  22.  
  23.     result += (a &  ( (int16_t)( ( b & (1 << n) ) << n2 ) ) / ( 1 << 15) ) << n;  
  24.   n++; n2--;
  25.  
  26.     result += (a &  ( (int16_t)( ( b & (1 << n) ) << n2 ) ) / ( 1 << 15) ) << n;  
  27.   n++; n2--;
  28.  
  29.     result += (a &  ( (int16_t)( ( b & (1 << n) ) << n2 ) ) / ( 1 << 15) ) << n;  
  30.   n++; n2--;
  31.  
  32.     result += (a &  ( (int16_t)( ( b & (1 << n) ) << n2 ) ) / ( 1 << 15) ) << n;  
  33.   n++; n2--;
  34.  
  35.     result += (a &  ( (int16_t)( ( b & (1 << n) ) << n2 ) ) / ( 1 << 15) ) << n;  
  36.   n++; n2--;
  37.  
  38.     result += (a &  ( (int16_t)( ( b & (1 << n) ) << n2 ) ) / ( 1 << 15) ) << n;  
  39.   n++; n2--;
  40.  
  41.     result += (a &  ( (int16_t)( ( b & (1 << n) ) << n2 ) ) / ( 1 << 15) ) << n;  
  42.   n++; n2--;
  43.  
  44.     result += (a &  ( (int16_t)( ( b & (1 << n) ) << n2 ) ) / ( 1 << 15) ) << n;  
  45.   n++; n2--;
  46.  
  47.     result += (a &  ( (int16_t)( ( b & (1 << n) ) << n2 ) ) / ( 1 << 15) ) << n;  
  48.   n++; n2--;
  49.  
  50.     result += (a &  ( (int16_t)( ( b & (1 << n) ) << n2 ) ) / ( 1 << 15) ) << n;  
  51.   n++; n2--;
  52.  
  53.     result += (a &  ( (int16_t)( ( b & (1 << n) ) << n2 ) ) / ( 1 << 15) ) << n;  
  54.   n++; n2--;
  55.  
  56.     result += (a &  ( (int16_t)( ( b & (1 << n) ) << n2 ) ) / ( 1 << 15) ) << n;  
  57.   return result;
  58. }
  59.  
  60. int main(void)
  61. {
  62.  
  63.   uint16_t a, b;
  64.   a = 0;
  65.   b = 0;
  66.  
  67.   do
  68.   {
  69.     if (multiply(a, b) != a * b)
  70.  
  71.  
  72.       fprintf(stderr,
  73.                "ERROR:\n"
  74.                "my: %u\n"
  75.                "norm: %u\n"
  76.                "%hu * %hu\n"
  77.                "\n",
  78.                multiply(a, b), (a * b),a, b
  79.              );
  80.  
  81.     if (UINT16_MAX == a)
  82.     {
  83.       b++;
  84.     }
  85.     a++;
  86.   //fprintf(stderr, "%hu * %hu\n", a, b);
  87.   } while ( ( a != 0 ) || (b != 0) );
  88.  
  89.   fprintf(stderr, "%"PRIu16"* ""%"PRIu16"\n", a, b);
  90.   printf("Done!\n");
  91.  
  92.   return 0;
  93. }
Time limit exceeded #stdin #stdout 5s 1784KB
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https://ideone.com/NlMluL
language:
C (gcc 8.3)
created:
10 years ago
visibility:
public

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