整数中1出现的次数（从1到n整数中出现的次数）

class Solution {
public:
    int NumberOf1Between1AndN_Solution(int n)
    {
        if(n <= 0) return 0;
        int sum = 0;
        while(n){
            sum += weishu(n);
            n--;
        }
        return sum;
    }
    int weishu(int n){
        int sum = 0;
        while(n){
            if(n % 10 == 1)
                sum++;
            n /= 10;
        }
        return sum;
    }
};