用log(N)的解法实现数值的整数次方

 

//

//  main.m

//  c++test

//

//  Created by andyyang on 6/3/13.

//  Copyright (c) 2013 andyyang. All rights reserved.

//



//#import <Foundation/Foundation.h>

#include "stdio.h"

#include "string.h"



int power(double base,int exponent)

{

 if(exponent==0)

 {

     return 1;

 }

    if(exponent==1)

    {

        return base;

    }

    if(exponent &0x01)

    {

        return power(base,exponent>>1)*power(base,exponent>>1)*base;

    }else

    {

        return power(base,exponent>>1)*power(base,exponent>>1);

    }

}

int main(int argc, const char * argv[])

{

    double ret=power(12, 2);

    printf("%f",ret);

    getchar();    

    return 0;

}

充分利用位运算，高效低实现数值的整数次方