UVa 10519 - !! Really Strange !!

题意

n个圆圈做多能划分几个区域

思路

目测法

代码

import java.math.*;import java.io.*;import java.util.*;public class Main {    static public void main(String[] args) {        Scanner in = new Scanner(System.in);        while (in.hasNext()) {            BigInteger n = in.nextBigInteger();            if (n.compareTo(BigInteger.ZERO) == 0) {                System.out.println("1");                continue;            }            n = n.multiply(n.subtract(BigInteger.ONE)).add(BigInteger.valueOf(2));            System.out.println(n);        }    }}