题解 | #分苹果#

import java.io.BufferedReader; import java.io.InputStreamReader; import java.io.IOException; public class Main{ public static void main(String[] args)throws IOException{ BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); int n = Integer.parseInt(in.readLine()); String str = null; int[] num = new int[n]; int[] num1 = new int[n]; int sum = 0; int total = 0; while((str = in.readLine()) != null){ String[] s = str.split(" "); for(int i = 0;i < n;i++){ num[i] = Integer.parseInt(s[i]); } } sum = sum(num);

    if(sum % n == 0){
        int temp = sum / n;
        for(int i = 0;i < n;i++){
            num1[i] = num[i] - temp;
        }
        int flag = 0;
        for(int i = 0;i < n;i++){
           if(num1[i] % 2 != 0){
              flag = 1;
              System.out.println(-1);
               break;
           }
            
        }
        if(flag == 0){
            int sum1 = 0;
            for(int i = 0;i < n;i++){
                if(num1[i] > 0) sum1 += num1[i];
            }
            total = sum1 /2;
            System.out.println(total);
        }
        
        
    }else{
        System.out.println(-1);
    }
}

public static boolean isDiv(int sum,int n){
    if(sum % n == 0) return true;
    else return false;
}
public static int sum(int[] num){
    int sum = 0;
    for(int i : num){
        sum += i;
        
    }
    return sum;
}

}