给定下列程序,那么执行printf("%\n",foo(20,13)); 的输出结果是多少? int foo (int x,int y ) { if (x<=0││y<=0) return 1; return 3*foo(x-6,y/2); } 3 9 27 81
int foo (int x,int y ) { if (x<=0││y<=0) return 1; return 3*foo(x-6,y/2); }
3
9
27
81