#3796
Find Maximum Value in a Constrained Sequence
MediumArrayGreedyGreedyDynamic Programming
Approaches
Brute ForceOptimal
Complexity Comparison
| Brute Force | Optimal Solution★ | |
|---|---|---|
| Time | O(n²) | O(n) |
| Space | O(1) | O(n) |
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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.
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Algorithm
3 steps- 1Step 1: Initialize an array 'a' with zeros and apply restrictions to set upper bounds.
- 2Step 2: Traverse from left to right, updating a[i] = min(a[i-1] + diff[i-1], a[i]) to respect the diff constraints.
- 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)ℹ
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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