LintCode 1046 · Prime Number of Set Bits in Binary Representation.java

	public class Solution {
	/**
	* @param L: an integer
	* @param R: an integer
	* @return: the count of numbers in the range [L, R] having a prime number of set bits in their binary representation
	*/
	public int countPrimeSetBits(int L, int R) {
	// handle corner cases
	int counter = 0;
	for (int i = L; i <= R; i++) {
	if (isPrimeSetBits(i)) {
	counter++;
	}
	}
	return counter;
	}
	private boolean isPrimeSetBits(int i) {
	int counter = 0;
	while (i > 0) {
	if (i % 2 == 1) {
	counter++;
	}
	i /= 2;
	}
	return isPrime(counter);
	}
	private boolean isPrime(int number) {
	if (number < 2) {
	return false;
	}
	for (int i = 2; i <= Math.sqrt(number); i++) {
	if (number % i == 0) {
	return false;
	}
	}
	return true;
	}
	}

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