Pos(x, n)
Implement pow(x, n), which calculates x raised to the power n (i.e., xn).
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| Example 1:
Input: x = 2.00000, n = 10
Output: 1024.00000
Example 2:
Input: x = 2.10000, n = 3
Output: 9.26100
Example 3:
Input: x = 2.00000, n = -2
Output: 0.25000
Explanation: 2-2 = 1/22 = 1/4 = 0.25
Constraints:
-100.0 < x < 100.0
-231 <= n <= 231-1
n is an integer.
Either x is not zero or n > 0.
-104 <= xn <= 104
|
Solution
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| class Solution {
public:
double myPow(double x, int n) {
if (n == 0) {
return 1.0;
}
double absX = abs(x);
int absN = abs(n);
double tmp = myPow(absX, absN / 2);
bool isNegativeX = x < 0 && n % 2 == 1;
bool isNegativeN = n < 0;
double ans;
if (absN % 2 == 0) {
ans = tmp * tmp;
} else {
ans = tmp * tmp * absX;
}
return (isNegativeX ? -1.0 : 1.0) * (isNegativeN ? 1.0 / ans : ans);
}
};
|
