338. Counting Bits

public class Solution {
    public int[] countBits(int num) {
        int n[] = new int[num+1];
        int base = 1;
        n[0] = 0;
        for(int i=1, t=0; i<=num; i++, t++) {
            if(i == base) {
                t = 0;
                base *= 2;
            }
            n[i] = n[t] + 1;
        }
        return n;
    }
}