{ "data": { "question": { "questionId": "3032", "questionFrontendId": "2836", "boundTopicId": null, "title": "Maximize Value of Function in a Ball Passing Game", "titleSlug": "maximize-value-of-function-in-a-ball-passing-game", "content": "
You are given a 0-indexed integer array receiver
of length n
and an integer k
.
There are n
players having a unique id in the range [0, n - 1]
who will play a ball passing game, and receiver[i]
is the id of the player who receives passes from the player with id i
. Players can pass to themselves, i.e. receiver[i]
may be equal to i
.
You must choose one of the n
players as the starting player for the game, and the ball will be passed exactly k
times starting from the chosen player.
For a chosen starting player having id x
, we define a function f(x)
that denotes the sum of x
and the ids of all players who receive the ball during the k
passes, including repetitions. In other words, f(x) = x + receiver[x] + receiver[receiver[x]] + ... + receiver(k)[x]
.
Your task is to choose a starting player having id x
that maximizes the value of f(x)
.
Return an integer denoting the maximum value of the function.
\n\nNote: receiver
may contain duplicates.
\n
Example 1:
\n\nPass Number | \n\t\t\tSender ID | \n\t\t\tReceiver ID | \n\t\t\tx + Receiver IDs | \n\t\t
---|---|---|---|
\n\t\t\t | \n\t\t\t | \n\t\t\t | 2 | \n\t\t
1 | \n\t\t\t2 | \n\t\t\t1 | \n\t\t\t3 | \n\t\t
2 | \n\t\t\t1 | \n\t\t\t0 | \n\t\t\t3 | \n\t\t
3 | \n\t\t\t0 | \n\t\t\t2 | \n\t\t\t5 | \n\t\t
4 | \n\t\t\t2 | \n\t\t\t1 | \n\t\t\t6 | \n\t\t
\nInput: receiver = [2,0,1], k = 4\nOutput: 6\nExplanation: The table above shows a simulation of the game starting with the player having id x = 2. \nFrom the table, f(2) is equal to 6. \nIt can be shown that 6 is the maximum achievable value of the function. \nHence, the output is 6. \n\n\n
Example 2:
\n\nPass Number | \n\t\t\tSender ID | \n\t\t\tReceiver ID | \n\t\t\tx + Receiver IDs | \n\t\t
---|---|---|---|
\n\t\t\t | \n\t\t\t | \n\t\t\t | 4 | \n\t\t
1 | \n\t\t\t4 | \n\t\t\t3 | \n\t\t\t7 | \n\t\t
2 | \n\t\t\t3 | \n\t\t\t2 | \n\t\t\t9 | \n\t\t
3 | \n\t\t\t2 | \n\t\t\t1 | \n\t\t\t10 | \n\t\t
\nInput: receiver = [1,1,1,2,3], k = 3\nOutput: 10\nExplanation: The table above shows a simulation of the game starting with the player having id x = 4. \nFrom the table, f(4) is equal to 10. \nIt can be shown that 10 is the maximum achievable value of the function. \nHence, the output is 10. \n\n\n
\n
Constraints:
\n\n1 <= receiver.length == n <= 105
0 <= receiver[i] <= n - 1
1 <= k <= 1010
x
and for every i
in the range [0, ceil(log2k)]
, we can determine the last receiver's id and compute the sum of player ids who receive the ball after 2i
passes, starting from x
.last_receiver[x][i] =
the last receiver's id after 2i
passes, and sum[x][i] =
the sum of player ids who receive the ball after 2i
passes. For all x
in the range [0, n - 1]
, last_receiver[x][0] = receiver[x]
, and sum[x][0] = receiver[x]
.i
in range [1, ceil(log2k)]
, last_receiver[x][i] = last_receiver[last_receiver[x][i - 1]][i - 1]
and sum[x][i] = sum[x][i - 1] + sum[last_receiver[x][i - 1]][i - 1]
, for all x
in the range [0, n - 1]
.x
, we can now go through the powers of 2
in the binary representation of k
and make jumps corresponding to each power, using the pre-computed values, to compute f(x)
.f(x)
from each player id.Compiled with clang 11
using the latest C++ 20 standard.
Your code is compiled with level two optimization (-O2
). AddressSanitizer is also enabled to help detect out-of-bounds and use-after-free bugs.
Most standard library headers are already included automatically for your convenience.
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Most standard library headers are already included automatically for your convenience.
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Python 2.7.12
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Node.js 16.13.2
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