Count Increasing Quadruplets - Practice Coding | SlaveCode
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2552. Count Increasing Quadruplets
Hard
50 Points
Array
Dynamic Programming
Binary Indexed Tree
Enumeration
Prefix Sum
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:
Examples
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.
2552. Count Increasing Quadruplets
Hard
50 Points
Array
Dynamic Programming
Binary Indexed Tree
Enumeration
Prefix Sum
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:
Examples
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.