LeetCode 1502. Can Make Arithmetic Progression From Sequence

Description

https://leetcode.com/problems/can-make-arithmetic-progression-from-sequence/

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

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
• -10^6 <= arr[i] <= 10^6

Explanation

Sort first. Then compare the differences between numbers.

Python Solution

class Solution:
    def canMakeArithmeticProgression(self, arr: List[int]) -> bool:
        arr = sorted(arr)
        
        diff = arr[1] - arr[0]
        prev = arr[1]
        
        for num in arr[2:]:
            if num - prev != diff:
                return False
            prev = num
        
        return True