CareerCup

Do not really get the point, anyway, here is the power function.

#include <iostream>

double power(double x, int y)
{
	if (y < 0)
		return 1 / power(x, -y);

	double res = 1;
	double base = x;

	while (y > 0)
	{
		if (y & 1 == 1)
		{
			res *= base;
		}
		base *= base;
		y >>= 1;
	}

	return res;
};


int main()
{
	double res = power(2, 5);

	return 0;
}

(x^y + y^x)+(x^y - y^x)+(x^y/y^x)+(x^y*y^x)
This is your question?

public static int improvePowCompute(int obj,int times){

HashMap<Integer,Integer> result_hold=new HashMap<Integer,Integer>();
result_hold.put(0, 1);
result_hold.put(1, obj);
return compute_process(obj,times,result_hold);
}

public static int compute_process(int obj,int times,HashMap<Integer,Integer> result_hold){
if(times<0){
return Integer.MIN_VALUE;
}
if(times%2==0){
if(result_hold.containsKey(times/2)){
int tmp=result_hold.get(times/2);
result_hold.put(times, tmp*tmp);
return tmp*tmp;
}
else{
int tmp=compute_process(obj,times/2,result_hold);
result_hold.put(times, tmp);
return tmp*tmp;
}
}
else{
if(result_hold.containsKey((times-1)/2)){
int tmp=result_hold.get((times-1)/2);
result_hold.put(times, tmp*tmp*obj);
return tmp*tmp*obj;
}
else{
int tmp=compute_process(obj,(times-1)/2,result_hold);
result_hold.put(times, tmp*tmp*obj);
return tmp*tmp*obj;
}
}
}

expressing the power as a sum of powers of two, evaluating each of the terms by left shift and then multiplying them would be a better option.
For example, 5^6=5^(2+4)=(5^2)*(5^4)
These two operations can be done by simple left shift.
How abt this idea??

ideone.com/n5aqx
 
import java.util.*;
import java.lang.*;
 
class Main
{
        public static void pow(int a, int b)
        {
                double val1 = 1, val2 = 1;
 
                if (b!=0)
                {
                        int counter = Math.abs(b);
                        while(counter>0)
                        {
                                if (b<0)
                                {
                                        val1 /= a;
                                }
                                else
                                {
                                        val1 *= a;
                                }
                                counter--;
                        }
 
                        for(int i=0;i<a;i++)
                        {
                                val2 *= b;
                        }
                }
                else
                {
                        val1 = 0;
                        val2 = 0;
                }
 
                System.out.println("Val1: "+val1);
                System.out.println("Val2: "+Math.ceil(val2));
 
        }
 
        public static void main (String[] args) throws java.lang.Exception
        {
                pow(2, -4);
        }
}