Arithmetic Slices

Author: anantkaushik

413-arithmetic-slices.py

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+"""
+Problem Link: https://leetcode.com/problems/arithmetic-slices/
+
+An integer array is called arithmetic if it consists of at least three elements and if the difference between any two consecutive elements is the same.
+For example, [1,3,5,7,9], [7,7,7,7], and [3,-1,-5,-9] are arithmetic sequences.
+Given an integer array nums, return the number of arithmetic subarrays of nums.
+A subarray is a contiguous subsequence of the array.
+
+Example 1:
+Input: nums = [1,2,3,4]
+Output: 3
+Explanation: We have 3 arithmetic slices in nums: [1, 2, 3], [2, 3, 4] and [1,2,3,4] itself.
+
+Example 2:
+Input: nums = [1]
+Output: 0
+
+Constraints:
+1 <= nums.length <= 5000
+-1000 <= nums[i] <= 1000
+"""
+class Solution:
+ def numberOfArithmeticSlices(self, nums: List[int]) -> int:
+ if len(nums) < 3:
+ return 0
+ 
+ diff = float('inf') 
+ ap_arrays = cur_length = 0
+ 
+ for index in range(1, len(nums)):
+ if nums[index] - nums[index-1] == diff:
+ cur_length += 1
+ else:
+ diff = nums[index] - nums[index-1]
+ cur_length = 2
+ 
+ if cur_length >= 2:
+ ap_arrays += (cur_length - 2)
+ 
+ return ap_arrays