题解 | #整数中1出现的次数

import java.util.*;
public class Solution {
    public int NumberOf1Between1AndN_Solution(int n) {
        int sum = 0;
        //将每个数转化为字符串
        for (int i = 1; i <= n; i++) {
            String str = i + "";
            //统计字符串的'1'
            for (int j = 0; j < str.length(); j++) {
                //相等就累加
                if (str.charAt(j) == '1') {
                    sum++;
                }
            }
        }


        return sum;
    }
}