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 1:
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 2:
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
-
-105 <= nums[i] <= 105
SOLUTION:
from collections import Counter
class Solution:
def isAP(self, arr):
n = len(arr)
if n == 1:
return True
arr = Counter(arr)
a = min(arr)
b = max(arr)
d = (b - a) // (n - 1)
if d == 0 and len(arr) == 1:
return True
for i in range(n):
if arr[a + i * d] != 1:
return False
return True
def checkArithmeticSubarrays(self, nums: List[int], l: List[int], r: List[int]) -> List[bool]:
n = len(l)
return [self.isAP(nums[l[i]:r[i]+1]) for i in range(n)]
Top comments (0)