[LeetCode]Sqrt(x)@python

Implement

int sqrt(int x)

.

Compute and return the square root of x.

x is guaranteed to be a non-negative integer.

Example 1:

Input: 4
Output: 2

Example 2:

Input: 8
Output: 2
Explanation: The square root of 8 is 2.82842..., and since we want to return an integer, the decimal part will be truncated.

方法一：暴力穷举（略）

方法二：二分法（略）

方法三：牛顿法

原理见这里

class Solution(object):
def mySqrt(self, x):
"""
:type x: int
:rtype: int
"""
r = x
while r*r > x:
r = (x/r+r)/2
return r