53 lines
740 B
C++
53 lines
740 B
C++
#include <bits/stdc++.h>
|
|
using namespace std;
|
|
|
|
class Solution {
|
|
public:
|
|
double myPow(double x, long long n) {
|
|
if (x == 0) return 0;
|
|
if (n == 0) return 1;
|
|
|
|
bool isNeg = n < 0;
|
|
n = abs(n);
|
|
|
|
int logn = (int)log2(n);
|
|
|
|
vector<double> expTable{x};
|
|
|
|
for (int i = 1; i < logn + 1; i++) {
|
|
expTable.emplace_back(expTable.back() * expTable.back());
|
|
}
|
|
|
|
double result = 1.0;
|
|
for (int i = 0; i < logn + 1; i++) {
|
|
if (n & 1) result *= expTable[i];
|
|
n >>= 1;
|
|
}
|
|
|
|
if (isNeg) result = 1.0 / result;
|
|
|
|
return result;
|
|
}
|
|
};
|
|
|
|
/*
|
|
|
|
1010
|
|
&0001
|
|
-----
|
|
0
|
|
|
|
101
|
|
& 001
|
|
-----
|
|
1
|
|
|
|
x^10
|
|
|
|
x^8 1
|
|
x^4 0
|
|
x^2 1
|
|
x^1 0
|
|
|
|
*/
|