338.Counting_Bits.java

class Solution {
  public int[] countBits(int n) {
    int[] ans = new int[n + 1];
    for (int i = 1; i <= n; ++i)
      ans[i] = ans[i / 2] + (i % 2 == 0 ? 0 : 1);
    return ans;
  }
}