Pow(x, n)

Description

Implement pow(x, n), which calculates x raised to the power n (i.e. xⁿ).

 

Example 1:

Input: x = 2.00000, n = 10
Output: 1024.00000

Example 2:

Input: x = 2.10000, n = 3
Output: 9.26100

Example 3:

Input: x = 2.00000, n = -2
Output: 0.25000
Explanation: 2-2 = 1/22 = 1/4 = 0.25

 

Constraints:

• -100.0 < x < 100.0
• -231 <= n <= 231-1
• -104 <= xn <= 104

Solution(javascript)

// O(n)
// const myPow = (x, n) => {
//   if (n === 0) {
//     return 1
//   }
//   let temp = 1
//   for (let i = 1; i <= Math.floor(Math.abs(n / 2)); i++) {
//     temp *= x
//   }
//   const result = n % 2 === 0 ? temp * temp : x * temp * temp
//   return n > 0 ? result : 1 / result
// }

const myPow = (x, n) => {
  if (n === 0) {
    return 1
  }
  const temp = myPow(x, Math.floor(Math.abs(n / 2)))
  const result = n % 2 === 0 ? temp * temp : x * temp * temp
  return n < 0 ? 1 / result : result
}