Sort Integers by The Number of 1 Bits.java

// Runtime: 9 ms (Top 70.77%) | Memory: 42.3 MB (Top 96.77%)
class Solution {
    public int[] sortByBits(int[] arr) {

        Integer[] arrInt = new Integer[arr.length];

        for(int i=0;i<arr.length;i++) {
            arrInt[i]=arr[i];
        }

        Arrays.sort(arrInt, new Comparator<Integer>() {
            @Override
            public int compare(Integer a, Integer b) {
                int aBits=numOfBits(a);
                int bBits=numOfBits(b);
                if(aBits==bBits) {
                    return a-b;
                }
                return aBits-bBits;
            }
        });

        for(int i=0;i<arr.length;i++) {
            arr[i]=arrInt[i];
        }
        return arr;
    }

    public int numOfBits(int a) {
        int bits=0;
        while(a!=0) {
            bits+=a&1;
            a=a>>>1;
        }

        return bits;
    }
}