How to add a condition so I don't go inside the loop

Question

I am working on a code where you subtract respective elements of array 'a' from array'b' till you get all elements in array 'a' equal.
Condition is that a[i]>b[i] for subtraction.
But not every time getting all elements equal is possible, so in that case I would like my code to print '-1', how can I achieve it.
I really tried hard to figure it out, don't give complex solutions as I am a beginner. you can subtract as many times you want.

Scanner sc = new Scanner(System.in);
    short n = sc.nextShort();
    short a[] = new short[n];
    short b[] = new short[n];
    for (short i = 0; i < n; i++) {// taking elements input
        a[i] = sc.nextShort();
    }
    for (short i = 0; i < n; i++) {// taking elements input
        b[i] = sc.nextShort();
    }
    short minimumOfArraya = 0;
    for (short i = 0; i < n; i++) {// finding smallest element in array 'a'
        for (short j = 0; j < n; j++) {
            if (a[i] < a[j]) {
                minimumOfArraya = a[i];
            }
        }
    }

    boolean allequal = false;
    int counter = 0;
    
    while (!allequal) {
        for (short i = 0; i < n; i++) {// subtracting elements
            if (a[i] == minimumOfArraya)
                continue;
            if (a[i] >= b[i]) {
                a[i] -= b[i];
                counter++;
            }

        }
        for (short i = 0; i < n; i++) {
            if (a[0] == a[i]) {
                allequal = true;
            } else {
                allequal = false;
                break;
            }

        }
    }
    for (int i = 0; i < n; i++) {// printing array 'a'
        System.out.print(a[i] + " ");
    }
    System.out.println();
    System.out.println(counter);


4
5 7 4 3//infinite loop
4 1 0 0

working input
5
5 7 10 5 15
2 2 1 3 5
output
5 5 5 5 5 
8

Answer 1

The minimum can be found faster:

short minimumOfArraya = Short.MAX_VALUE;
for (short i = 0; i < n; i++) {// finding smallest element in array 'a'
    if (a[i] < minimumOfArraya]) {
        minimumOfArraya = a[i];
    }
}

The for loop to check whether all are equal should initially have an allequal true, and on finding a false, break. The initial setting to true was missing.

boolean allequal = false;
int counter = 0;

while (!allequal) {
    for (short i = 0; i < n; i++) {// subtracting elements
        if (a[i] == minimumOfArraya)
            continue;
        if (a[i] >= b[i]) {
            a[i] -= b[i];
            counter++;
        }
    }
    allequal = true;
    for (short i = 0; i < n; i++) {
        allequal = a[0] == a[i];
        if (!allequal) {
            break;
        }
    }
}

If counter was not increased inside the while, the code may very well stay looping till overflow. If the minimum was 100 and 102 got 98 for instance.

Answer 2

If some of iterations producing number which is less than minimum, it clearly shows that you cannot make all elements equal. Check that after subtracting

while (!allequal) {
    boolean impossible = false;
    for (short i = 0; i < n; i++) {
        if (a[i] < mimimumofArraya) {
            impossible = true;
            break;
        }

        if (a[i] == minimumOfArraya) continue;

        if (a[i] >= b[i]) {
            a[i] -= b[i];
            counter++;
        }
    }

    if (impossible) {
        counter = -1;
        break;
    }

    // The rest of your loop
    ...
 }