Package g0401_0500.s0446_arithmetic_slices_ii_subsequence

Class Solution

  • All Implemented Interfaces:
    
public final class Solution

    446 - Arithmetic Slices II - Subsequence\.

    Hard

    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.

    A 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

    • <code>-2<sup>31</sup><= numsi<= 2<sup>31</sup> - 1</code>

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description

    • Field Summary

      Fields 
      Modifier and Type Field Description

    • Constructor Summary

      Constructors 
      Constructor Description
      Solution()

    • Enum Constant Summary

      Enum Constants 
      Enum Constant Description

    • Method Summary

      Modifier and Type Method Description
      final Integer numberOfArithmeticSlices(IntArray arr)

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait