Package g2501_2600.s2552_count_increasing_quadruplets

Class Solution

java.lang.Object

g2501_2600.s2552_count_increasing_quadruplets.Solution

public class Solution
extends Object

2552 - Count Increasing Quadruplets.

Hard

Given a 0-indexed integer array nums of size n containing all numbers from 1 to n, return the number of increasing quadruplets.

A quadruplet (i, j, k, l) is increasing if:

• 0 <= i < j < k < l < n, and
• nums[i] < nums[k] < nums[j] < nums[l].

Example 1:

Input: nums = [1,3,2,4,5]

Output: 2

Explanation:

• When i = 0, j = 1, k = 2, and l = 3, nums[i] < nums[k] < nums[j] < nums[l].

• When i = 0, j = 1, k = 2, and l = 4, nums[i] < nums[k] < nums[j] < nums[l]. There are no other quadruplets, so we return 2.

Example 2:

Input: nums = [1,2,3,4]

Output: 0

Explanation:

There exists only one quadruplet with i = 0, j = 1, k = 2, l = 3, but since nums[j] < nums[k], we return 0.

Constraints:

• 4 <= nums.length <= 4000
• 1 <= nums[i] <= nums.length
• All the integers of nums are unique. nums is a permutation.

Constructor Summary

Constructors

Constructor	Description
Solution()

Method Summary

Modifier and Type	Method	Description
long	countQuadruplets(int[] nums)

Methods inherited from class java.lang.Object

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

Constructor Detail

Solution

public Solution()

Method Detail

countQuadruplets

public long countQuadruplets(int[] nums)