1630.ArithmeticSubarrays.py

"""
    A sequence of numbers is called arithmetic if it consists of at least two 
    elements, and the difference between every two consecutive elements is the 
    same. More formally, a sequence s is arithmetic if and only if 
    s[i+1] - s[i] == s[1] - s[0] for all valid i.

    For example, these are arithmetic sequences:
        1, 3, 5, 7, 9
        7, 7, 7, 7
        3, -1, -5, -9

    The following sequence is not arithmetic:
        1, 1, 2, 5, 7

    You are given an array of n integers, nums, and two arrays of m integers 
    each, l and r, representing the m range queries, where the ith query is 
    the range [l[i], r[i]]. All the arrays are 0-indexed.

    Return a list of boolean elements answer, where answer[i] is true if the 
    subarray nums[l[i]], nums[l[i]+1], ... , nums[r[i]] can be rearranged to 
    form an arithmetic sequence, and false otherwise.

    Example:
    Input: nums = [4,6,5,9,3,7], 
           l = [0,0,2], 
           r = [2,3,5]
    Output: [true,false,true]
    Explanation:
                 In the 0th query, the subarray is [4,6,5]. This can be 
                 rearranged as [6,5,4], which is an arithmetic sequence.
                 In the 1st query, the subarray is [4,6,5,9]. This cannot be 
                 rearranged as an arithmetic sequence.
                 In the 2nd query, the subarray is [5,9,3,7]. This can be 
                 rearranged as [3,5,7,9], which is an arithmetic sequence.

    Example:
    Input: nums = [-12,-9,-3,-12,-6,15,20,-25,-20,-15,-10], 
           l = [0,1,6,4,8,7], 
           r = [4,4,9,7,9,10]
    Output: [false,true,false,false,true,true]

    Constraints:
        - n == nums.length
        - m == l.length
        - m == r.length
        - 2 <= n <= 500
        - 1 <= m <= 500
        - 0 <= l[i] < r[i] < n
        - -10**5 <= nums[i] <= 10**5
"""
#Difficulty: Medium
#101 / 101 test cases passed.
#Runtime: 176 ms
#Memory Usage: 14.3 MB

#Runtime: 176 ms, faster than 98.44% of Python3 online submissions for Arithmetic Subarrays.
#Memory Usage: 14.3 MB, less than 5.45% of Python3 online submissions for Arithmetic Subarrays.

class Solution:
    def checkArithmeticSubarrays(self, nums: List[int], l: List[int], r: List[int]) -> List[bool]:
        answer = []
        for i in range(len(l)):
            answer.append(self.checkCurrentSubarray(nums[l[i]:r[i]+1]))
        return answer
    
    def checkCurrentSubarray(self, sequence):
        sequence.sort()
        difference = sequence[1] - sequence[0]
        for j in range(2, len(sequence)):
            if sequence[j] - sequence[j-1] != difference:
                return False
        return True