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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <string.h>
  4.  
  5. #define N 14
  6. void f(int p, int *a, int n) {
  7.   int i;
  8.   if (n == p) {
  9.     for (i = 0; i < n; i++)
  10.       printf("%c, ", a[i] + 'a');
  11.     putchar('\n');
  12.   } else {
  13.     int *b;
  14.     if ((b = malloc(sizeof(int) * n)) != 0) {
  15.       for (i = 0; i < n; i++)
  16.         if (a[i] < 0) {
  17.           memcpy(b, a, sizeof(int) * n);
  18.           b[i] = p;
  19.           f(p + 1, b, n);
  20.         }
  21.       free(b);
  22.     }
  23.   }
  24. }
  25.  
  26. #define N 14
  27. int main(int argc, char *argv[]) {
  28.   int *a, n, i;
  29.   if (argc != 2) {
  30.   usage:
  31.     printf("usage: %s <num>\n", argv[0]);
  32.     printf("1 < <num> < %d\n", N + 1);
  33.     return 1;
  34.   }
  35.  
  36.   if ((n = atoi(argv[1])) <= 1 || n > N)
  37.     goto usage;
  38.   if ((a = malloc(sizeof(int) * n)) != 0) {
  39.     for (i = 0; i < N; i++)
  40.       a[i] = -1;
  41.     f(0, a, n);
  42.     free(a);
  43.   }
  44.   return 0;
  45. }
  46. /* end */
  47.  
Runtime error #stdin #stdout 0.01s 1720KB
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stdin
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Standard input is empty
stdout
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usage: ./prog <num>
1 < <num> < 15
https://ideone.com/d5CFS
language:
C (gcc 8.3)
created:
12 years ago
visibility:
public

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