Practice Count Increasing Quadruplets
Read the task, work through the examples, and check your approach against the constraints. Use the original LeetCode task for coding and submissions.
Hard#2552
LeetCode ProblemCount Increasing Quadruplets
Problem Statement
Count quadruples of indices i < j < k < l in nums satisfying nums[i] < nums[k] < nums[j] < nums[l]. The input is a permutation of integers 1 through n.
Source: Count Increasing Quadruplets on LeetCode. Use the original task for its coding environment and submissions.
Examples
# Example 1
Input
nums = [1,3,2,4,5]
Output
2
# Example 2
Input
nums = [1,2,3,4]
Output
0
Constraints
4 <= nums.length <= 4000
1 <= nums[i] <= nums.length
All the integers of nums are unique. nums is a permutation.
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