Pow(x, n) -leetcode

Pow(x, n)

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Implement pow(x, n).

class Solution {
public:
    double pow(double x, int n) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        if (fabs(x) < 1e-7 || fabs(x - 1) < 1e-7)
            return x;
        
        if (n < 0 ) {
            n += 1;//防止负数溢出
            return (1.0 / (x*pow(x, -n)));
        }
        if (n == 0)
            return 1.0;
        if (n == 1) {
            return x;
        }
        if (n == 2)
            return x*x;
        return (n %2 == 0 ? pow(pow(x,n/2), 2) : x*pow(pow(x, (n-1)/2), 2));
    }
};