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🐱(binary-search): 50. Pow(x, n)

补充 Python 题解

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Original file line number	Diff line number	Diff line change
`@@ -288,12 +288,35 @@ class Solution(object):`
`288`	`288`
`289`	`289`	`[原题链接](https://leetcode-cn.com/problems/powx-n/)`
`290`	`290`
`291`		`-### 思路:二分`
	`291`	`+### 思路:快速幂`
`292`	`292`
`293`	`293`	`利用分治的思想,$x^2n$ 均可以写作 $x^n * x^n$。`
`294`	`294`
`295`	`295`	`递归:`
`296`	`296`
	`297`	`+<!-- tabs:start -->`
	`298`	`+`
	`299`	`+#### Python`
	`300`	`+`
	`301`	+```python
	`302`	`+class Solution:`
	`303`	`+ def myPow(self, x: float, n: int) -> float:`
	`304`	`+ def fast_pow(x, n):`
	`305`	`+ if n == 0:`
	`306`	`+ return 1`
	`307`	`+`
	`308`	`+ fast_res = fast_pow(x, n//2)`
	`309`	`+ if n % 2 == 0:`
	`310`	`+ return fast_res * fast_res`
	`311`	`+ else:`
	`312`	`+ return fast_res * fast_res * x`
	`313`	`+`
	`314`	`+ res = fast_pow(x, abs(n))`
	`315`	`+ return res if n > 0 else 1/res`
	`316`	+```
	`317`	`+`
	`318`	`+#### Go`
	`319`	`+`
`297`	`320`	```go
`298`	`321`	`func myPow(x float64, n int) float64 {`
`299`	`322`	`if n >= 0 {`
`@@ -318,6 +341,8 @@ func quickMul(x float64, n int) float64 {`
`318`	`341`	`}`
`319`	`342`	```
`320`	`343`
	`344`	`+<!-- tabs:end -->`
	`345`	`+`
`321`	`346`	`## 69. x 的平方根`
`322`	`347`
`323`	`348`	`[原题链接](https://leetcode-cn.com/problems/sqrtx/comments/)`

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