[goldman]OA test 2025 Start – 6 Jan

1. Process Scheduler

Process scheduling algorithms are used by a CPU to optimally schedule the running processes. A core can execute one process at a time, but a CPU may have multiple cores.

There are n processes where the iᵗʰ process starts its execution at start[i] and ends at end[i], both inclusive. Find the minimum number of cores required to execute the processes.

Example
n = 3
start = [1, 3, 4]
end = [3, 5, 6]

If the CPU has only one core, the first process starts at 1 and ends at 3. The second process starts at 3. Since both processes need a processor at 3, they overlap. There must be more than 1 core.

If the CPU has two cores, the first process runs on the first core from 1 to 3, the second runs on the second core from 3 to 5, and the third process runs on the first core from 4 to 6.

Return 2, the minimum number of cores required.


Function Description
Complete the function getMinCores in the editor below.

getMinCores takes the following arguments:

  • int start[n]: the start times of processes
  • int end[n]: the end times of processes

Returns
int: the minimum number of cores required

Constraints
1 ≤ n ≤ 10⁵
1 ≤ start[i], end[i] ≤ 10⁹


Sample Input For Custom Testing
STDIN
3
1 2 3
3 3 5

Function
start[] size n = 3
start = [1, 2, 3]
end[] size n = 3
end = [3, 3, 5]

Sample Output
3

Explanation
Using 2 cores, the first and second processes finish at time 3. The third process starts at 3. Given the conflict, there must be at least 1 more core.


2. Transaction Simplification

Implement a prototype service to simplify a group of debt transactions.

There are n people, and a list of m debts amongst them where debts[i] = [from[i], to[i], amount[i]] represents that person from[i] owes the person to[i] an amount of amount[i].

Given the array debts, find the minimum number of transactions required to clear all the debts.

Example
Suppose n = 3, m = 4, debts[] = [[0, 1, 20], [1, 0, 5], [1, 2, 10], [2, 0, 10]]

Suppose 0 gives 1 a total amount of 5 units.

fromtoamount
0120 - 5 = 15
105
1210
2010

Also, 1 owed 0 5 units, so reduce the debt from 1 to 0 by that 5 units. Now 0 and 1's debts are simplified.

fromtoamount
0110
2010

The three transactions can now cancel each other out. Only one transaction is required to clear all the debts, i.e., from 0 to 1. Hence, the answer is 1.


Function Description
Complete the function getMinTransactions in the editor below.

getMinTransactions has the following parameters:

  • n: the number of people
  • debt[m][3]: the debts

Returns
int: the minimum number of transactions required

Constraints
2 ≤ n ≤ 9
2 ≤ m ≤ 10⁵
0 ≤ debt[i][0], debt[i][1] < n
1 ≤ debt[i][2] ≤ 10⁹


Sample Input For Custom Testing

Sample Case 0
STDIN
3
2
3
0 1 10
2 0 5

Function
n = 3
m = 2
size of debt[i] = 3
debts[] = [[0, 1, 10], [2, 0, 5]]

Sample Output
2

Explanation
Person 2 must pay person 0 5 units, and person 0 must pay person 1 10 units.


Sample Case 1
STDIN
4
4
3
1 2 15
3 2 14
0 3 10
3 1 20

Function
n = 4
m = 4
size of debt[i] = 3
debts[] = [[1, 2, 15], [3, 2, 14], [0, 3, 10], [3, 1, 20]]

Sample Output
3


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