给定一个double类型的浮点数base和int类型的整数exponent。求base的exponent次方。
保证base和exponent不同时为0
考虑快速幂
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| class Solution {
public:
double Power(double base, int exponent) {
bool need_reverse = false;
if (exponent < 0)
{
exponent = - exponent;
need_reverse = true;
}
if (exponent == 0)
{
return 1;
}
else if (exponent == 1)
{
if (need_reverse)
{
return 1 / base;
}
else
{
return base;
}
}
else
{
double res = 1;
while (exponent)
{
if (exponent & 1)
{
res *= base;
}
base *= base;
exponent >>= 1;
}
if (need_reverse)
{
return 1 / res;
}
else
{
return res;
}
}
}
};
|