arithmetic_progression.js

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

 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
 **/


/**
 * @param {number[]} arr
 * @return {boolean}
 */
var canMakeArithmeticProgression = function(arr) {
    arr.sort((a, b)=>a - b);
    let diff = Math.abs(arr[0] - arr[1]);
    for (let i = 0; i < arr.length - 1; ++i){
        if (Math.abs(arr[i] - arr[i+1]) !== diff) return false;
    }
    return true;
};