Sort a bit vector in O(n) time

BitSort.java

import java.util.BitSet;

public class BitSort {
	
	public BitSet sort(BitSet bits) {
		// Count the number of ones: O(n)
		int numOnes = bits.cardinality();
		
		// Overwrite the array with the ones first followed by the zeros
		bits.set(0, numOnes);
		bits.clear(numOnes, bits.size());
		
		return bits;
	}

}