calculate-powxn

Given two integers x and n, write a function to compute xn. We may assume that x and n are small and overflow doesn’t happen. We can't use Math library.

Input : x = 2, n = 3
Output : 8


Input : x = 7, n = 2
Output : 49
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public class Solution {
    public static double power(double base, int exp) {
       return 0.0

    }

    public static void main(String[] args) {
      boolean testsPass = true;
        double result =  power(2,-2);
        // System.out.println(result);
        // testsPass = testsPass && result == 59049.0;
        testsPass = testsPass && power(2,-2) == 0.25;
        testsPass = testsPass && power(2,2) == 4;
        testsPass = testsPass && power(3,10) == 59049.0;

        if (testsPass) {
            System.out.println("Pass");
        } else {
            System.out.println("There are failures");
        }
    }
}
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Recursive approach

public static double power(double base, int exp) {
    if (exp == 0)
        return 1;
    if (exp < 1)
        return 1 / power(base, -exp);

    if (exp % 2 == 1) {
        return base * power(base * base, (exp - 1) / 2);
    } else {
        return power(base * base, (exp) / 2);
    }
}
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Time complexity: Log(n)
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