算法学习笔记

---

layout: post
title: “算法”
date: 2018-06-20 09:12
comments: true
tags:
- C/C++
- 算法
- 随笔

---

判断是否是2的幂

https://www.exploringbinary.com/ten-ways-to-check-if-an-integer-is-a-power-of-two-in-c/

https://blog.youkuaiyun.com/K346K346/article/details/53316953

Shift Right

int isPowerOfTwo (unsigned int x)
{
 while (((x & 1) == 0) && x > 1) /* While x is even and > 1 */
   x >>= 1;
 return (x == 1);
}

Decrement and Compare

int isPowerOfTwo (unsigned int x)
{
  return ((x != 0) && !(x & (x - 1)));
}

Complement and Compare

int isPowerOfTwo (unsigned int x)
{
  return ((x != 0) && ((x & (~x + 1)) == x));