#include <cstdio>

void print_partitions(int sum_val, int n) {
  int pos = 0, last = n - 1;
  int a[n]; // dynamic stack-allocated arrays are a gcc extension
  for (int i = 1; i != n; ++i)
    a[i] = 0;
  a[0] = sum_val;
  while (true) {
    for (int i = 0; i != last; ++i)
        printf("%3d ", a[i]);
    printf("%3d\n", a[last]);
    if (pos != last) {
      --a[pos];
      ++pos;
      a[pos] = 1;
    }
    else {
      if (a[last] == sum_val)
        return;
      for (--pos; a[pos] == 0; --pos);
      --a[pos];
      int tmp = 1 + a[last];
      ++pos;
      a[last] = 0;
      a[pos] = tmp;
    }
  }
}

int main() {
  print_partitions(12, 5);
  return 0;
}