#2334

Subarray With Elements Greater Than Varying Threshold

Hard
ArrayStackUnion-FindMonotonic StackSliding WindowTwo Pointers
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Approaches

Brute ForceOptimal
Complexity Comparison
Brute ForceOptimal Solution
Time
O(n²)
O(n)
Space
O(1)
O(1)
💡

Intuition

Time O(n)Space O(1)

This approach uses a sliding window technique to efficiently find the longest subarray where all elements are greater than the threshold divided by the length of the subarray. It reduces unnecessary checks by maintaining a window and adjusting its size dynamically.

⚙️

Algorithm

4 steps
  1. 1Step 1: Calculate the required value as threshold / k.
  2. 2Step 2: Initialize two pointers (left and right) to represent the current window of elements.
  3. 3Step 3: Expand the right pointer to include elements in the window until the window size exceeds k or an element is found that is not greater than the required value.
  4. 4Step 4: If the window size is exactly k and all elements are valid, return k. If not, move the left pointer to shrink the window and continue checking.
solution.py9 lines
1def findSubarray(nums, threshold, k):
2    required_value = threshold / k
3    left = 0
4    for right in range(len(nums)):
5        if nums[right] <= required_value:
6            left = right + 1
7        if right - left + 1 == k:
8            return k
9    return -1

Complexity note: This complexity is achieved because we traverse the array with a single pass using two pointers, making it linear in terms of the number of elements.

  • 1The minimum element in the subarray must be greater than threshold / k for the entire subarray to be valid.
  • 2Using a sliding window approach allows us to efficiently find valid subarrays without redundant checks.

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