2022-02-12 (338. Bit count)

class Solution {
    
    public int[] countBits(int n) {
    
        int[] result=new int[n+1];
        for(int i=0;i<=n;++i){
    
            result[i]=oneCount(i);
        }
        return result;
    }
    public int oneCount(int x){
    
        int count=0;
        while(x!=0){
    
            x=x&(x-1);
            ++count;
        }
        return count;
    }
}

Dynamic programming ：

class Solution {
    
    public int[] countBits(int n) {
    
        int[] result=new int[n+1];
        for(int i=1;i<=n;++i){
    
            result[i]=result[i&(i-1)]+1;
        }
        return result;
    }
}