Jackie1210/leetcode

This repo is just for relearning algorithms and DS.

leetcode

This repo is just for leetcode.

TIPS

利用|和空格将英文字符转换为小写

String.fromCharCode('a'.charCodeAt() | ' '.charCodeAt()) === 'a'
String.fromCharCode('A'.charCodeAt() | ' '.charCodeAt()) === 'a'

利用&和_将英文字符转换为大写

String.fromCharCode('A'.charCodeAt() & '_'.charCodeAt()) === 'A'
String.fromCharCode('a'.charCodeAt() & '_'.charCodeAt()) === 'A'

利用^和空格在大小写之间进行转换

String.fromCharCode('A'.charCodeAt() ^ ' '.charCodeAt()) === 'a'
String.fromCharCode('a'.charCodeAt() ^ ' '.charCodeAt()) === 'A'

判断两个数字异号

-1 ^ 2 = -3

消除数字 n 的二进制表示中的最后一个 1

n & (n - 1)

判断一个数是不是2的指数

function isPowerOf2(num){
  if (num < 0) return false
  return (num & (num - 1)) === 0
}