50. Pow(x, n)

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

# @lc code=start
using LeetCode

function my_pow(x::Float64, n::Int)::Float64
    n == 0 && return 1
    if n < 0
        x, n = 1 / x, -n
    end
    res, extra = x, 1
    while n > 1
        n & 1 == 1 && (extra *= res)
        res *= res
        n >>= 1
    end
    return res * extra
end
# @lc code=end

my_pow (generic function with 1 method)

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