public static void main(String[] args) {
String result= factrial(100);
System.out.println(result);
}
//计算两个数的乘积
private static String product(String a,String b){
//将字符串b转变为整形数字
int intb=Integer.parseInt(b);
int[] ints=new int[a.length()];
//将数字字符串String转换为整形数组ints
for (int i = 0; i < a.length(); i++) {
ints[i]=Integer.parseInt(a.substring(i,i+1));
}
//将ints[i]数组*数字b将其放入ints数组中
for (int i = 0; i < ints.length; i++) {
ints[i]=intb*ints[i];
}
//进位操作 得到存为ints数组的结果
for (int i =ints.length-1; i >0; i--) {
ints[i-1]=ints[i-1]+ints[i]/10;
ints[i]=ints[i]%10;
}
//将数组的结果拼接为字符串
StringBuilder str=new StringBuilder("");
for (int i = 0; i < ints.length; i++) {
str.append(ints[i]);
}
return str.toString();
}
//递归
private static String factrial(int n){
if(n==1) return "1";
else return product(factrial(n-1),Integer.toString(n));
}