#2836

Maximize Value of Function in a Ball Passing Game

Hard
ArrayDynamic ProgrammingBit ManipulationDynamic ProgrammingBinary LiftingGraph Traversal
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Approaches

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

Intuition

Time O(n log k)Space O(n log k)

The optimal solution uses a technique called binary lifting to efficiently compute the score after k passes. Instead of simulating each pass, we can jump directly to the player who would receive the ball after a certain number of passes, reducing the time complexity significantly.

⚙️

Algorithm

3 steps
  1. 1Step 1: Precompute the next player for each player using binary lifting.
  2. 2Step 2: For each player, calculate the total score for k passes using the precomputed values.
  3. 3Step 3: Return the maximum score found.
solution.py20 lines
1def maxScore(receiver, k):
2    n = len(receiver)
3    max_score = 0
4    log_k = k.bit_length()
5    jump = [[0] * log_k for _ in range(n)]
6    for i in range(n):
7        jump[i][0] = receiver[i]
8    for j in range(1, log_k):
9        for i in range(n):
10            jump[i][j] = jump[jump[i][j-1]][j-1]
11    for i in range(n):
12        current_score = 0
13        current_player = i
14        for j in range(log_k):
15            if k & (1 << j):
16                current_score += current_player
17                current_player = jump[current_player][j]
18        current_score += current_player
19        max_score = max(max_score, current_score)
20    return max_score

Complexity note: The time complexity is O(n log k) because we preprocess the jump table in O(n log k) and then compute scores in O(n log k) as well, making it efficient even for large k.

  • 1Understanding the relationship between players and how the ball is passed is crucial for optimizing the solution.
  • 2Binary lifting allows us to efficiently compute the result without simulating every pass.

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