Alternate adding and subtracting a number java

Question

Here's my current code:

Scanner input = new Scanner(System.in);
int n, sum = 0;
System.out.println("Enter n:");
n = input.nextInt();
for (int i = 1; i <= n; i++) {
    if (i % 2 == 0){
        sum-=input.nextInt();
    } else {
        sum+=input.nextInt();
    }
}
System.out.println("The total sum is:"+sum);

Can someone please help to alternately add and minus an integer?

For example, if I enter n: = 5 and ask the user to enter 4, 14, 5, 6, 1 then it will compute like 4 + 14 - 5 + 6 - 1

Answer 1

You were almost there:

for (int i = 1; i <= n; i++) {
    if (i > 2 && i % 2 != 0){
        sum-=input.nextInt();
    } else {
        sum+=input.nextInt();
    }
}

The first two numbers contribute to the result with the "plus" sign, their sign does not alternate, hence the additional i > 2 condition.

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Side note: I would suggest renaming sum to result and changing the output text to something like System.out.println("The result is:"+result);. The reason is that it's not the sum being calculated, to the name sum is a bit confusing.

Answer 2

int result = 0;
for (int  i = 1; i <= n; i++) {
    int num = input.nextInt();
    result += (i == 1 || i % 2 == 0) ? num : -num;
}