# 位运算的简单应用

## 基本概念

• int a = 1; 变量a实际的表示为0000…0001，共32位
• 右移>>n位：去掉二进制后的n位
• 左移<<n位：在二进制数后面填上n个0，$(1 << n = 2^n)$
• 按位与或非

# 山东大学（威海）程序设计竞赛2020新星赛（线上模拟赛）题解

## factorial（数论，简单模拟）

In many applications very large integers numbers are required. Some of these applications are using keys for secure transmission of data, encryption, etc. In this problem you are given a number, you have to determine the number of digits in the factorial of the number.