剑指offer之 整数中1出现的次数

public class Solution {
    public int NumberOf1Between1AndN_Solution(int n) {
        int count=0;
        for(int i=1;i<=n;i++){

            count+=core(i);
        }

        return count;
    }
    private int core(int n){
        int num=0;
        while(n!=0){
            if(n%10==1){
                num++;
            }
            n/=10;
        }
        return num;
    }
}