21 【程序 21 求阶乘】
题目:求 1+2!+3!+...+20!的和
程序分析:此程序只是把累加变成了累乘。
package cskaoyan; public class cskaoyan21 {
@org.junit.Test
public void sum() {
int mix = 1;
int max = 20;
long total = 0; for (int i = mix; i <= max; i++) {
total += factorial(i);
} System.out.println(total);
} private long factorial(long number) {
if (number == 1 || number == 0) {
return 1;
} else {
return number * factorial(number - 1);
}
}
}