[LEETCODE] 1502. Can Make Arithmetic Progression From Sequence

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TITLE : 1502. Can Make Arithmetic Progression From Sequence

Description : 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

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  길이 2 이상의 정수가 담긴 배열이 주어졌을 때, 어떻게든 연속하는 두 원소의 차이가 항상 동일하도록 할 수 있으면 Arithmetic progression 하다고 정의한다. 주어진 배열에 대해서 Arithmetic progression 한 지를 true/false 를 반환하면 된다. 이를 위해 내림차순으로 정렬한 뒤, 각각의 원소들간의 차이가 일정한지 체크해주면 된다.

 

[C++]

class Solution {
public:
    bool canMakeArithmeticProgression(vector<int>& arr) {
        sort(arr.begin(), arr.end());
        int diff = 0; int check = arr[1] - arr[0];
        for (int i = 1; i < arr.size(); i++) {
            diff = arr[i] - arr[i - 1];
            if (check != diff) return false;
        } return true;
    }
};