class Solution {
    public int[] countBits(int num) {
        int[] res = new int[num+1];
        int mi = 1;
        int pre = 1;
        for(int i=1;i<=num;i++){
            if(i==mi){//到达2的幂次方,1的个数为1
                res[i] = 1;
                pre = mi;
                mi = mi<<1;
            }else{
                res[i] = 1+res[i-pre];//最高位的1+去掉最高位后前面得到的值
            }
        }
        return res;
    }
}