#1601
Maximum Number of Achievable Transfer Requests
HardArrayBacktrackingBit ManipulationEnumeration
Approaches
Brute ForceOptimal
Complexity Comparison
| Brute Force | Optimal Solution★ | |
|---|---|---|
| Time | O(n²) | |
| Space | O(1) |
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Intuition
Time Space
Instead of checking all combinations, we can use a backtracking approach to explore the requests and keep track of the net changes dynamically. This is like exploring paths in a maze, where we backtrack when we hit a dead end.
⚙️
Algorithm
3 steps- 1Step 1: Use a backtracking function to explore each request.
- 2Step 2: Maintain a count of requests that can be fulfilled.
- 3Step 3: For each request, either include it in the count or skip it and check the next request.
solution.py20 lines
1def maximumRequests(n, requests):
2 def backtrack(index, count, net_change):
3 nonlocal max_count
4 if index == len(requests):
5 if all(change == 0 for change in net_change):
6 max_count = max(max_count, count)
7 return
8 # Include the current request
9 fr, to = requests[index]
10 net_change[fr] -= 1
11 net_change[to] += 1
12 backtrack(index + 1, count + 1, net_change)
13 net_change[fr] += 1
14 net_change[to] -= 1
15 # Exclude the current request
16 backtrack(index + 1, count, net_change)
17
18 max_count = 0
19 backtrack(0, 0, [0] * n)
20 return max_countSolutions and explanations are original Tejav content. Problem titles © LeetCode — use the LeetCode button above for the full problem statement.