Minimum processing time

Array Greedy Sorting

70.2% acceptance

Feb 25, 2026

282

You have a certain number of processors, each having 4 cores. The number of tasks to be executed is four times the number of processors. Each task must be assigned to a unique core, and each core can only be used once. You are given an array processorTime representing the time each processor becomes available and an array tasks representing how long each task takes to complete. Return the minimum time needed to complete all tasks.

Solution

Rust

Time O(n log n)

Space O(1)

LeetCode

solution.rs

impl Solution {
  pub fn min_processing_time(mut processor_time: Vec<i32>, mut tasks: Vec<i32>) -> i32 {
    processor_time.sort();
    tasks.sort_by(|a, b| b.cmp(a)); // descending
    // Assign 4 longest tasks to processor with smallest start time
    let mut ans = 0;
    for (i, &pt) in processor_time.iter().enumerate() {
      // Tasks assigned: 4*i, 4*i+1, 4*i+2, 4*i+3
      let finish = pt + tasks[4 * i]; // max is the first (largest) task
      ans = ans.max(finish);
    }
    ans
  }
}