第十一届蓝桥杯Java省赛第二场B组第一题

 

public class Main {
	public static void main(String[] args) {
		int sum = 0;
		for (int i = 1; i <= 2020; i++) {
			String ls = i + "";
			for (int j = 0; j < ls.length(); j++) {
				if (ls.charAt(j) == '2') {
					sum++;
				}
			}
		}
		System.out.println(sum);//624
	}
}