使用开方是重点。

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import java.util.Scanner;
public class Main {public static void main(String[] args) {Scanner scanner = new Scanner(System.in);int N = scanner.nextInt(); //输入Nint count = 0;for (int i = 1; i <= N; i++) { //统计1-N中符合条件的if (fun(i)){count++;}}System.out.println(count);}//判断数是否符合条件public static boolean fun(int x){int n = (int) Math.sqrt(x); //（重要！！！）for (int i = 2; i <= n; i++) {if (x%i==0 && x/i!=i){return true;}}return false;}
}