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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3.  
  4. void combinations(int **sets, int *sizes, int *indices, int n, int depth, int *output, int *count) {
  5.     if (depth == n) {
  6.         // base case: we have selected one element from each set
  7.         // print the combination
  8.         for (int i = 0; i < n; i++) {
  9.             printf("%d", sets[i][indices[i]]);
  10.         }
  11.         printf("\n");
  12.         // add the combination to the output array
  13.         for (int i = 0; i < n; i++) {
  14.             output[*count * n + i] = sets[i][indices[i]];
  15.         }
  16.         (*count)++;
  17.         return;
  18.     }
  19.     // recursive case: select one element from the current set and move on to the next set
  20.     for (int i = 0; i < sizes[depth]; i++) {
  21.         indices[depth] = i;
  22.         combinations(sets, sizes, indices, n, depth + 1, output, count);
  23.     }
  24. }
  25.  
  26. int main() {
  27.     int n = 2;
  28.     int *sizes = malloc(n * sizeof(int));
  29.     sizes[0] = 3;
  30.     sizes[1] = 2;
  31.     int **sets = malloc(n * sizeof(int *));
  32.     sets[0] = malloc(3 * sizeof(int));
  33.     sets[0][0] = 1;
  34.     sets[0][1] = 2;
  35.     sets[0][2] = 3;
  36.     sets[1] = malloc(2 * sizeof(int));
  37.     sets[1][0] = 2;
  38.     sets[1][1] = 5;
  39.     int *indices = calloc(n, sizeof(int));
  40.     int count = 0;
  41.     int *output = malloc(n * sizes[0] * sizes[1] * sizeof(int));
  42.     combinations(sets, sizes, indices, n, 0, output, &count);
  43.     printf("Total combinations: %d\n", count);
  44.     for (int i = 0; i < count; i++) {
  45.         for (int j = 0; j < n; j++) {
  46.             printf("%d", output[i * n + j]);
  47.         }
  48.         printf("\n");
  49.     }
  50.     free(sizes);
  51.     free(sets[0]);
  52.     free(sets[1]);
  53.     free(sets);
  54.     free(indices);
  55.     free(output);
  56.     return 0;
  57. }
  58.  
Success #stdin #stdout 0s 5456KB
comments (?)
stdin
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Standard input is empty
stdout
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12
15
22
25
32
35
Total combinations: 6
12
15
22
25
32
35
https://ideone.com/sZSJjL
language:
C (gcc 8.3)
created:
1 year ago
visibility:
public

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