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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <tgmath.h>
  4.  
  5.  
  6. int main()
  7. {
  8.     long N;
  9.     scanf("%d", &N);
  10.     N = abs (N);
  11.     long T = round(sqrt(N)) +1 ;
  12.     long a[T];
  13.     int Z = 0;
  14.     unsigned long i = 0;
  15.     while (i <= T) {
  16.         a[i] = 1;
  17.         if (i == 0)
  18.             a[i] = 0;
  19.         i++;
  20.     }
  21.     for (unsigned long i = 2;  i <= T; i++) //43
  22.         if (a[i] == 1) {
  23.             if (N % i == 0)
  24.                 Z = 1;
  25.             for (unsigned long j = i*i; j <= T; j += i)
  26.                 a[j] = 0;
  27.         }
  28.     if (Z != 1) {
  29.         for (unsigned long i = T; i > 0; i--)
  30.             if ((a[i] != 0) && (N % i == 0)) {
  31.                 printf("%lu", i);
  32.                 break;
  33.             }
  34.     }
  35.     else
  36.     {
  37.         printf("%lu", N);
  38.     }
  39.     return 0;
  40. }
  41.  
  42.  
Success #stdin #stdout 0s 10528KB
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https://ideone.com/QLWUT8
language:
C (gcc 8.3)
created:
6 years ago
visibility:
public

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