Question

java计算1/2+2!/3+3!/4+5!/6+...+(n-1)!/n直到最后一项大于1000

Answer 1

当n = 9的时候满足条件
public class Du {

public static void main(String[] args) {

boolean isNFound = false;
int fac = 1;
int i = 1;
double sum = 0;
double num=0;

while (!isNFound) {
fac *= i;
num = (double) fac / (i + 1);
isNFound = num > 1000;

if (!isNFound) {
sum += fac / (i + 1);
}

i++;
}

System.out.println("The max n is: " + i);

System.out.println((i-1) + "!/" + (i) + "=" + num);
System.out.println("1/2 + 2!/3 + 3!/4 + ... + " + (i-1) + "!/" + i + " = " + sum);

}

}
--------------
The max n is: 9
8!/9=4480.0
1/2 + 2!/3 + 3!/4 + ... + 8!/9 = 757.0

Answer 2

private static double factorial(int n){
if(n==1){
return 1;
}
return n * factorial(n-1);
}

public static double calculate(int n){
if(n==1){
return 1;
}

double nFactorialValue = factorial(n);
double tmpValue = nFactorialValue / n;
return tmpValue + calculate(n-1);
}
public static void main(String[] args){
System.out.println( calculate(1000) );
}

Answer 3

public int getResult(){
int sum = 0;
int k=1;
for(int i=1;i<1000;i++){
for(int m=0;m<i;m++){
k=k*(m+1);
}
k=k/i;
sum=sum+k;
if(k>1000){
System.out.println(sum-k);
System.out.println(k);
System.out.println(i);
break;
}
k=1;
}

return sum;
}

Answer 4

恩恩，不多说，简单的递归函数调用，你懂得.......