D3=1-3d3/d2是什么意思

include #include int jc(int m){ if(m!=1) return m*jc(m-1); else return 1; } int c(int m,int n){ if(m>=n) return jc(m)/(jc(n)*jc(m-n)); } int main(void){ int m,n; scanf("%d%d",&m,&n); printf("%d\n",c(m,n))