leetcode 50. Pow(x, n)

50. Pow(x, n)

Implement pow(x, n).

Example 1:

Input: 2.00000, 10Output: 1024.00000

Example 2:

Input: 2.10000, 3Output: 9.26100

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class Solution {public:    double myPow(double x, int n)     {        long nn = n;        if(nn == 0)            return 1;        else if(x == 1)            return x;        else if(x==-1)            return ( n % 2 == 0) ? 1 : -1;        else if(nn < 0)        {            x = 1 / x;            nn = -nn;        }              double sum = 1.00000;            for (long i = 1; i <= nn; i++)        {            sum = sum * x;            if(abs(sum) < 0.000000001)                return 0.00000;        }        return sum;       }};