Sword finger offer 16 Integer power of numeric value

The finger of the sword Offer 16. Integer power of value

Medium difficulty 310
Realization pow(x, n) , Computation x Of n Power function （ namely ,xn）. Do not use library functions , At the same time, there is no need to consider the problem of large numbers .

 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 explain ：2-2 = 1/22 = 1/4 = 0.25

Tips ：

• -100.0 < x < 100.0
• -231 <= n <= 231-1
• -104 <= xn <= 104

Ideas

• Fast power
• Long N=n
• x=1/x;

Code

class Solution {
    
public:
    double myPow(double x, int n) {
    
        long N=n;	// Easy conversion n,-2147483648 Can also be converted to a positive number 

        double res=1.0;
        if(n<0){
    
            N=-N;
            x=1/x;	// During calculation , There is no need to make judgment 
        }

        while(N){
    
            int a=N%2;
            N>>=1;
            if(a==1)    res*=x;
            x*=x;
        }
        return res;
    }
};