| 请阅读下面的程序,在空白处填写正确的代码,实现下列功能。用递归方法求出n!。int fac(int n){ int t; if( ) return 1; else { t = ; return t; }}void main(){ int m, y; printf("Enter m : "); scanf("%d", &m); if (m<0) printf("Input data Error! "); else { y = fac(m); printf(" %d!= %d ", m, y); }}