The sword refers to OFFER----16, the integer power of the value (js implementation)

topic

• Implement pow(x, n) , which computes the n-th power function of x (ie, xn). Library functions must not be used, and large numbers need not be considered.
• leetcode link: https://leetcode-cn.com/problems/shu-zhi-de-zheng-shu-ci-fang-lcof/

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ideas

• fast power

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code

var myPow = function (x, n) {
    
    
  if (n === 0) return 1
  let flag = n > 0
  n = n > 0 ? n : -n
  let mi = n // 幂
  let res = 1 // 额外的x乘积
  let di = x // 底数
  while (mi) {
    
    
    if (mi % 2) res *= di
    di *= di
    mi = Math.floor(mi / 2)
  }
  return flag ? res : 1 / res
}