public class MethodDemo
{
    public static void main(String[] args)
    {
        System.out.println("计算结果" +sum(100));
    }
    public static int sum(int num){
        if(num==1)
        {
            return 1;
        }
        else{
            return num+sum(num - 1);//小弟这道程序题总是迷茫  不知道如何计算的  请明白人指点迷津
        }
    }
}