So I wanted to solve this problem:

After a tennis tournament each player was asked how many matches he had.

An athlete can't play more than one match with another athlete.

As an input the only thing you have is the number of athletes and the matches each athlete had. As an output you will have 1 if the tournament was possible to be done according to the athletes answers or 0 if not. For example:

Input: 4 3 3 3 3 Output: 1

Input: 6 2 4 5 5 2 1 Output: 0

Input: 2 1 1 Output: 1

Input: 1 0 Output: 0

Input: 3 1 1 1 Output: 0

Input: 3 2 2 0 Output: 0

Input: 3 4 3 2 Output: 0

the first number of the input is not part of the athletes answer it's the number of athletes that took part in the tournament for example in 6 2 4 5 5 2 1 we have 6 athletes that took part and their answers were 2 4 5 5 2 1

This is what I have wrote so far and it is not working completely:

import java.util.Scanner; import java.util.Arrays; public class Tennis { public static void main(String[] args) { Scanner input = new Scanner(System.in); String N; int count; int sum = 0; int max; int activeAthletes; int flag; System.out.printf("Give: "); N = input.nextLine(); String[] arr = N.split(" "); int[] array = new int[arr.length]; for (count = 0; count < arr.length; count++) { array[count] = Integer.parseInt(arr[count]); //System.out.print(arr[count] + " "); } for (count = 1; count < arr.length; count++) { sum += array[count]; } //System.out.println("\n" + sum); activeAthletes = array[0]; for (count = 1; count < array.length; count++) { if (array[count] == 0) { activeAthletes--; } } max = array[1]; for (count = 2; count < array.length; count++) { if (array[count] > max) { max = array[count]; } } // System.out.println(max); if ((sum % 2 == 0) && (max < activeAthletes)) { flag = 1; } else{ flag = 0; } System.out.println(flag); } }