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Others/BrianKernighanAlgorithm.java
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@ -4,46 +4,37 @@ import java.util.Scanner;
/**
* @author Nishita Aggarwal
* <p>
* Brian Kernighan’s Algorithm
* <p>
* algorithm to count the number of set bits in a given number
* <p>
* Subtraction of 1 from a number toggles all the bits (from right to left) till the rightmost set bit(including the
* rightmost set bit).
* So if we subtract a number by 1 and do bitwise & with itself i.e. (n & (n-1)), we unset the rightmost set bit.
* <p>
* If we do n & (n-1) in a loop and count the no of times loop executes we get the set bit count.
* <p>
* <p>
* Time Complexity: O(logn)
* <p>Brian Kernighan’s Algorithm
* <p>algorithm to count the number of set bits in a given number
* <p>Subtraction of 1 from a number toggles all the bits (from right to left) till the
* rightmost set bit(including the rightmost set bit). So if we subtract a number by 1 and do
* bitwise & with itself i.e. (n & (n-1)), we unset the rightmost set bit.
* <p>If we do n & (n-1) in a loop and count the no of times loop executes we get the set bit
* count.
* <p>
* <p>Time Complexity: O(logn)
*/
public class BrianKernighanAlgorithm {
/**
* @param num: number in which we count the set bits
* @return int: Number of set bits
*/
static int countSetBits(int num) {
int cnt = 0;
while (num != 0) {
num = num & (num - 1);
cnt++;
}
return cnt;
/**
* @param num: number in which we count the set bits
* @return int: Number of set bits
*/
static int countSetBits(int num) {
int cnt = 0;
while (num != 0) {
num = num & (num - 1);
cnt++;
}
return cnt;
}
/**
* @param args : command line arguments
*/
public static void main(String args[]) {
Scanner sc = new Scanner(System.in);
int num = sc.nextInt();
int setBitCount = countSetBits(num);
System.out.println(setBitCount);
sc.close();
}
/** @param args : command line arguments */
public static void main(String args[]) {
Scanner sc = new Scanner(System.in);
int num = sc.nextInt();
int setBitCount = countSetBits(num);
System.out.println(setBitCount);
sc.close();
}
}