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.<p>Hard</p> <p>Given a <strong>0-indexed</strong> integer array <code>nums</code> of size <code>n</code> containing all numbers from <code>1</code> to <code>n</code>, return <em>the number of increasing quadruplets</em>.</p> <p>A quadruplet <code>(i, j, k, l)</code> is increasing if:</p> <ul> <li><code>0 <= i < j < k < l < n</code>, and</li> <li><code>nums[i] < nums[k] < nums[j] < nums[l]</code>.</li> </ul> <p><strong>Example 1:</strong></p> <p><strong>Input:</strong> nums = [1,3,2,4,5]</p> <p><strong>Output:</strong> 2</p> <p><strong>Explanation:</strong></p> <ul> <li> <p>When i = 0, j = 1, k = 2, and l = 3, nums[i] < nums[k] < nums[j] < nums[l].</p> </li> <li> <p>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.</p> </li> </ul> <p><strong>Example 2:</strong></p> <p><strong>Input:</strong> nums = [1,2,3,4]</p> <p><strong>Output:</strong> 0</p> <p><strong>Explanation:</strong></p> <p>There exists only one quadruplet with i = 0, j = 1, k = 2, l = 3, but since nums[j] < nums[k], we return 0.</p> <p><strong>Constraints:</strong></p> <ul> <li><code>4 <= nums.length <= 4000</code></li> <li><code>1 <= nums[i] <= nums.length</code></li> <li>All the integers of <code>nums</code> are <strong>unique</strong>. <code>nums</code> is a permutation.</li> </ul>

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 Details

Solution

public Solution()

Method Details

countQuadruplets

public long countQuadruplets(int[] nums)