projecteuler 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.

译文：

自然数1到10的平方之和为385，他们的和的平方为3025，现将自然数1到10的和的平方减去平方之和等于2640，求出自然数从1到100的和的平方减去平方之和。

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第一次code:

public class Main
{  
    public static void main(String[] args)
    {
        System.out.println(start(100)-run(100));
    }
    /**
     * 求前N项平方之和
     * @param n
     * @return
     */
    public static int run(int n)
    {
        int m=0;
        for(int i=0;i<n+1;i++)
        {
            m += i*i;
        }
        return m;
    }
    /**
     * 求前N项和的平方
     * @param n
     * @return
     */
    public static int start(int n)
    {
        int m=0,o=0;
        for(int i=0;i<n+1;i++)
        {
            m += i;
        }
        o = m*m;
        return o;
    }
}