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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <string.h>
  4. #include <math.h>
  5.  
  6. #define EPS 1E-6
  7.  
  8. int compare_newdouble(const void *left, const void *right);
  9. int compare_newdouble(const void *left, const void *right)
  10. {
  11.     double *p = (double*)left;
  12.     double *q = (double*)right;
  13.  
  14.     if(fabs(fabs(*p) - fabs(*q)) < EPS)
  15.     {
  16.         return 0;
  17.     }
  18.  
  19.     if(fabs(*p) > fabs(*q))
  20.     {
  21.         return 1;
  22.     }
  23.  
  24.     return -1;
  25. }
  26.  
  27. void arrswap(void *base, void *add);
  28. void arrswap(void *base, void *add)
  29. {
  30.     void *c;
  31.     c=base;
  32.     base=add;
  33.     add=c;
  34. }
  35.  
  36. void merge(void *base, void *add, size_t mid, size_t n, size_t size, int (*compar)(const void *, const void *));
  37. void merge(void *base, void *add, size_t mid, size_t n, size_t size, int (*compar)(const void *, const void *))
  38. {
  39.     size_t l = 0, r = 0, a = 0;
  40.  
  41.     while(l < mid && r < (n-mid))
  42.     {
  43.         if((*compar)((char*)base+size*l, (char*)base+size*mid+size*r) == -1)
  44.         {
  45.             memcpy(((char*)add+size*a), ((char*)base+size*l), size); // putting the memory from left to add
  46.             a++;
  47.             l++;
  48.         }
  49.         else
  50.         {
  51.             memcpy(((char*)add+size*a), ((char*)base+size*mid+size*r), size); // putting the memory from right to add
  52.             a++;
  53.             r++;
  54.         }
  55.     }
  56.  
  57.     if(l < mid)
  58.     {
  59.         memcpy(((char*)add+size*a), ((char*)base+size*l), size*(mid - l));
  60.     }
  61.  
  62.     if(r < (n-mid))
  63.     {
  64.         memcpy(((char*)add+size*a), ((char*)base+size*mid+size*r), size*(n-mid - r));
  65.     }
  66. }
  67.  
  68. void mergesort(void *base, size_t n, size_t size, int (*compar)(const void *, const void *));
  69. void mergesort(void *base, size_t n, size_t size, int (*compar)(const void *, const void *))
  70. {
  71.     size_t mid = n/2;
  72.     void* add=malloc(size*n);
  73.  
  74.     if(n < 2) // array length = 1
  75.     {
  76.         return;
  77.     }
  78.  
  79.     mergesort(base, mid, size, compar); //left array
  80.     mergesort((char*)base+size*mid, n-mid, size, compar); //right array
  81.  
  82.     merge(base, add, n/2, n, size, compar);
  83.  
  84.     arrswap(base, add);
  85.  
  86.     memcpy(base, add, size*n);
  87.  
  88.     free(add);
  89. }
  90.  
  91. int main(void)
  92. {
  93.     FILE *inp;
  94.     FILE *outp;
  95.     int n, i;
  96.     double *arr;
  97.  
  98.     inp=fopen("input.txt", "r");
  99.     outp=fopen("output.txt", "w");
  100.  
  101.     if(inp==NULL)
  102.     {
  103.         perror("Error. File input.txt cannot be found");
  104.         return -1;
  105.     }
  106.  
  107.     fscanf(inp, "%d ", &n);
  108.     arr=malloc(sizeof(double)*n);
  109.  
  110.     for(i = 0; i < n; i++)
  111.     {
  112.         fscanf(inp, "%lf ", &arr[i]);
  113.     }
  114.  
  115.     mergesort(arr, n, sizeof(double), &compare_newdouble);
  116.  
  117.     for(i = 0; i < n; i++)
  118.     {
  119.         fprintf(outp, "%lf ", arr[i]);
  120.     }
  121.  
  122.     printf("Done. \n");
  123.  
  124.     fclose(inp);
  125.     fclose(outp);
  126.     free(arr);
  127.  
  128.     return 0;
  129. }
Runtime error #stdin #stdout #stderr 0s 2284KB
comments (?)
stdin 
10

-10 9 8 -7 6 5.000001 5 -3 5 -1
stdout 
Standard output is empty
stderr 
Error. File input.txt cannot be found: Permission denied
https://ideone.com/Jt6hwq
language:
C (gcc 8.3)
created:
9 years ago
visibility:
public

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