题解 | [NOIP2010]数字统计
[NOIP2010]数字统计
https://www.nowcoder.com/practice/179d9754eeaf48a1b9a49dc1d438525a?tpId=290&tqId=39941&ru=/exam/oj
import java.util.Scanner;
//核心思想：枚举+拆分
public class Main {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
int l = in.nextInt();//输入L
int r = in.nextInt();//输入R
int count = 0;//计数器
for(int i=l;i<=r;i++){//通过for循环枚举l到r之间每一个数
int tmp = i;//判断2个数时,为了不改变i,此处用临时变量tmp来记录i的当前值
while(tmp!=0){
if(tmp%10==2){
count++;
}
tmp/=10;
}
}
System.out.println(count);//打印结果
}
}
