欧拉项目第六题 Sum square difference

The sum of the squares of the first ten natural numbers is,

12 + 22 + ... + 102 = 385
The square of the sum of the first ten natural numbers is,

(1 + 2 + ... + 10)2 = 552 = 3025
Hence the difference between the sum of the squares of the first ten natural numbers and the square of the sum is 3025 − 385 = 2640.
Find the difference between the sum of the squares of the first one hundred natural numbers and the square of the sum.

求(1+2+...+100)^2 - (1^2 + 2^2 + ... + 100^2)的值

public static void main(String[] args) {
        int total = 0;
        int end = 100;
        for(int i=1;i<=end;i++){
            for(int j=1;j<=end;j++) {
                if(i!=j)
                    total+=i*j;
            }
        }
        System.out.println(total);
    }