数据结构练习（33）数值的整数次方

#include <iostream>
#include <bitset>
using namespace std;

double PowerWithExponent_1(double base, size_t exp)
{
bitset<32> bits(exp);

if (bits.none())
return 1.0;

double b[32];
for (int i = 0; i < 32; ++i)
b[i] = 1.0;

double power = 1.0;
size_t cnt = 0;
for (int i = 0; i < 32 && cnt <= bits.count(); ++i)
{
if (i == 0)
power = base;
else
power *= power;

if (bits.at(i))
b[i] = power, ++cnt;
}

power = 1.0;
for (int i = 0; i < 32; ++i)
if (bits.at(i))
power *= b[i];

return power;
}

double PowerWithExponentRecursively(double base, unsigned int exp)
{
if (exp == 0)
return 1.0;

double power = PowerWithExponentRecursively(base, exp >> 1);
power *= power;

if (exp & 0x01)
power *= base;

return power;
}

int main()
{
double power1 = PowerWithExponent_1(2.3, 3);
double power2 = PowerWithExponentRecursively(2.3, 3);
cout << power1 << " " << power2 << endl;
return 0;
}