2010 年中兴面试题

编程求解：输入两个整数n 和m，从数列1，2，3.......n 中随意取几个数,使其和等于m ,要求将其中所有的可能组合列出来.

This is acombination generation problem.void findCombination(int n, int m) {  if (n>m) findCombination(m, m);  int aux[n];  memset(aux, 0, n*sizeof(int));  helper(m, 0, aux);}void helper(int dest, int idx, int aux[], int n){  if (dest == 0)    dump(aux, n);  if (dest <= 0 || idx==n) return;  helper(dest, idx+1, aux, n);  aux[idx] = 1;  helper(dest-idx-1, idx+1, aux, n);  aux[idx] = 0;}void dump(int aux[], int n) {  for (int i=0; i<n; i++)    if (aux) printf(“%3d”,i+1);  printf(“\n”);}PS: this is not an elegant implementation,however, it is not necessary to use gray code or other techniques for such aproblem, right?