#3796

Find Maximum Value in a Constrained Sequence

Medium
ArrayGreedyGreedyDynamic Programming
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Approaches

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

Intuition

Time O(n)Space O(n)

Use a greedy approach to propagate values from left to right and right to left, respecting both the diff and restrictions to maximize the sequence's largest value.

⚙️

Algorithm

3 steps
  1. 1Step 1: Initialize an array 'a' with zeros and apply restrictions to set upper bounds.
  2. 2Step 2: Traverse from left to right, updating a[i] = min(a[i-1] + diff[i-1], a[i]) to respect the diff constraints.
  3. 3Step 3: Traverse from right to left, updating a[i] = min(a[i+1] + diff[i], a[i]) to ensure all constraints are satisfied.
solution.py9 lines
1def maxValue(n, restrictions, diff):
2    a = [0] * n
3    for idx, maxVal in restrictions:
4        a[idx] = maxVal
5    for i in range(1, n):
6        a[i] = min(a[i], a[i-1] + diff[i-1])
7    for i in range(n-2, -1, -1):
8        a[i] = min(a[i], a[i+1] + diff[i])
9    return max(a)

Complexity note: The linear complexity comes from two passes through the array to enforce constraints, making it efficient.

  • 1Restrictions limit values directly and indirectly.
  • 2Greedy propagation ensures maximum values are achieved while respecting constraints.

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