SequenceSum

Sum of 'n' Numbers

sum_of_n (or SequenceSum.sumOfN in Java, SequenceSum.SumOfN in C#) takes an integer n and returns aList (an Array in Java/C#) of length abs(n) + 1. The List/Array contains the numbers in the arithmetic series produced by taking the sum of the consecutive integer numbers from 0 to n inclusive.

  • n can also be 0 or a negative value.

Example:

5 -> [0, 1, 3, 6, 10, 15]

-5 -> [0, -1, -3, -6, -10, -15]

7 -> [0, 1, 3, 6, 10, 15, 21, 28]

Linq的无形装逼太过致命了

public class SequenceSum
{
public static int[] SumOfN(int n)
{
//TODO: Write your solution here
return Enumerable.Range(, Math.Abs(n) + ).Select(item => Enumerable.Range(, item).Aggregate(, (x, y) => x + y)).Select(item => (n >= ) ? item : -item).ToArray();
}
}

需要注意的是,Enumerable.Range中第一个参数是起始数字,第二个参数是序列总个数Enumerable.Range(5,4)  结果是5,6,7,8

其他人的解法:

using System.Linq;

public class SequenceSum
{
public static int[] SumOfN(int n)
{
return Enumerable.Range(, n + ).Select(x => x * (x + ) / ).ToArray();
}
}

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