Ошибка - Если все три числа равны между собой, необходимо вывести все три.
package com.javarush.task.pro.task03.task0305;
import java.util.Scanner;
/*
Три числа
*/
public class Solution {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int a = scanner.nextInt();
int b = scanner.nextInt();
int c = scanner.nextInt();
boolean ab = (a == b);
boolean ac = (a == c);
boolean bc = (b == c);
if (ab && bc && ac)
System.out.println(a + " " + b + " " + c);
//else
//System.out.println("qwe");
if (ac)
System.out.println(a + " " + c);
if (bc)
System.out.println(b + " " + c);
if (ab)
System.out.println(a + " " + b);
scanner.close();
}
}