用Java编程求1+2+……+n

Question

如题所述

Answer 1

import java.util.Scanner;

public class Sum{
public static void main(String args[]){
System.out.print("Please enter n: ");
Scanner sc=new Scanner(System.in);
int n=sc.nextInt();

int sum=0;
for(int i=1;i<=n;i++)
sum+=i;
//用公式就是sum=n*(n+1)/2了。。。

System.out.println("The sum is "+sum);
}
}

Answer 2

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
public class HelloWorld{
public static void main(String[] args) throws NumberFormatException, IOException
{
System.out.print("请输入n ： ");
BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
int n = Integer.parseInt(input.readLine());
int sum = n * (n + 1) / 2;
System.out.print("1 + 2 + … + n = " + sum);
}
}

Answer 3

公式是 s=a1n+n(n-1)d/2
∵公差是1
∴s =1*n + (n*n -n)/2
∴s = n(n+1)/2;
public int getSum(int count){//count表示有多少个数字
return count(count+1)/2;
}本回答被提问者和网友采纳

Answer 4

你说的这个问题，这上面就有很详细的解决方案哦，他们的java教程很全面，你可以去了解下
参考资料:http://www.baidu.com/s?wd=%B1%B1%B7%E7%CD%F8&rsv_bp=0&rsv_spt=3&inputT=422

Answer 5

public class Test{
public int s(int n){
if(n==1){
return 1;
}
return n+s(n-1);
}
}