没人想到,把数字拼接成字符串 判断字符1的个数么?
好吧,面试可能会被虐

public class Solution {
    public int NumberOf1Between1AndN_Solution(int n) {
        String s = "";
        int number = 0;
        for(int i = 1; i<=n; i++){
            s = s + i;
        }
        char[] cs = s.toCharArray();
        for(int i = 0; i<cs.length; i++){
            if(cs[i]=='1'){
                number ++;
            }
        }
        return number;

    }
}