LeetCode 솔루션 분류

[11/27] 446. Arithmetic Slices II - Subsequence

컨텐츠 정보

본문

Given an integer array nums, return the number of all the arithmetic subsequences of nums.

A sequence of numbers 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.
  • For example, [1, 1, 2, 5, 7] is not an arithmetic sequence.

subsequence of an array is a sequence that can be formed by removing some elements (possibly none) of the array.

  • For example, [2,5,10] is a subsequence of [1,2,1,2,4,1,5,10].

The test cases are generated so that the answer fits in 32-bit integer.

 

Example 1:

Input: nums = [2,4,6,8,10]
Output: 7
Explanation: All arithmetic subsequence slices are:
[2,4,6]
[4,6,8]
[6,8,10]
[2,4,6,8]
[4,6,8,10]
[2,4,6,8,10]
[2,6,10]

Example 2:

Input: nums = [7,7,7,7,7]
Output: 16
Explanation: Any subsequence of this array is arithmetic.

 

Constraints:

  • 1  <= nums.length <= 1000
  • -231 <= nums[i] <= 231 - 1
Accepted
49,066
Submissions
120,562
태그

관련자료

댓글 1

학부유학생님의 댓글

  • 익명
  • 작성일
Runtime: 3267 ms, faster than 24.85% of Python3 online submissions for Arithmetic Slices II - Subsequence.
Memory Usage: 185.7 MB, less than 14.20% of Python3 online submissions for Arithmetic Slices II - Subsequence.
from collections import defaultdict
class Solution:
    def numberOfArithmeticSlices(self, nums: List[int]) -> int:
        dp = defaultdict(int)
        res = 0
        
        for e in range(1, len(nums)):
            for s in range(e):
                diff = nums[e] - nums[s]
                res += dp[(s, diff)]
                dp[(e, diff)] += dp[(s,diff)] + 1
        
        return res
LeetCode 솔루션 357 / 11 페이지
번호
제목
이름

최근글


인기글


새댓글


Stats


  • 현재 접속자 889 명
  • 오늘 방문자 5,462 명
  • 어제 방문자 6,932 명
  • 최대 방문자 14,831 명
  • 전체 회원수 1,481 명
알림 0