Brooke

一、題目

A sequence of numbers is called an arithmetic progression if the difference between any two consecutive elements is the same.

Given an array of numbers arr, return true if the array can be rearranged to form an arithmetic progression. Otherwise, return false.

 

Example 1:

Input: arr = [3,5,1] Output: true Explanation: We can reorder the elements as [1,3,5] or [5,3,1] with differences 2 and -2 respectively, between each consecutive elements.

Example 2:

Input: arr = [1,2,4] Output: false Explanation: There is no way to reorder the elements to obtain an arithmetic progression.

 

Constraints:

• 2 <= arr.length <= 1000
• -106 <= arr[i] <= 106

 

二、程式作法

public class Solution
{
    public bool CanMakeArithmeticProgression(int[] arr)
    {
        Array.Sort(arr);
        int diff = arr[1] - arr[0];

        for (int i = 1; i < arr.Length - 1; i++)
            if (arr[i] + diff != arr[i + 1])
                return false;
        return true;
    }
}

 

三、思路筆記

判斷一陣列是否為等差級數。