题解 | #挑7#

import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader;

public class Main { public static void main(String[] args) throws IOException { BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in)); String input = ""; while ((input = bufferedReader.readLine()) != null) { int count=0; int num=Integer.parseInt(input); for(int i=7;i<=num;i++){ if(i%7==0||contain7(i)){ count++; } } System.out.println(count); } }

public static boolean contain7(int n) {
    while (n > 0) {
        if (n % 10 == 7) {
            return true;
        } else {
            n /= 10;
        }
    }
    return false;
}

}