int[] a={1,2,3,4,5,6,7,8,9,10};
        System.out.println(f(a,0));
    }
}
//这段代码表示从begin开始,数组内所有数字的和...args){
        int[] a={1,2,3,4,5,6,7,8,9,10};
        System.out.println(f(a,9));
    }
}
//这段代码,表示数组中的从...args){
        int[] a={1,2,3,4,5,6,7,8,9,10};
        System.out.println(f(a,0,9));
    }
}
//这段代码表示数组内从