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Added Binary Exponentiation Fixes:#1943 #1945

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Merged
merged 3 commits into from
Nov 16, 2020
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Added Binary Exponentiation Fixes:#1943 #1945

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43ee4cc
Added Binary Exponentiation Fixes:#1943
Lakhan-Nad Oct 25, 2020
25300c1
tests added in Binary Exponentation #1945
Lakhan-Nad Nov 15, 2020
1f1893a
Assertion Added
Lakhan-Nad Nov 15, 2020
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46 changes: 46 additions & 0 deletions Maths/BinaryPow.java
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Original file line number Diff line number Diff line change
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package Maths;

public class BinaryPow {
/**
* Calculate a^p using binary exponentiation
* [Binary-Exponentiation](https://cp-algorithms.com/algebra/binary-exp.html)
*
* @param a the base for exponentiation
* @param p the exponent - must be greater than 0
* @return a^p
*/
public static int binPow(int a, int p) {
int res = 1;
while (p > 0) {
if ((p & 1) == 1) {
res = res * a;
}
a = a * a;
p >>>= 1;
}
return res;
}

/**
* Function for testing binary exponentiation
* @param a the base
* @param p the exponent
*/
public static void test(int a, int p) {
int res = binPow(a, p);
assert res == (int) Math.pow(a, p) : "Incorrect Implementation";
System.out.println(a + "^" + p + ": " + res);
}

/** Main Function to call tests
*
* @param args System Line Arguments
*/
public static void main(String[] args) {
// prints 2^15: 32768
test(2, 15);

// prints 3^9: 19683
test(3,9);
}
}