Description (leetcode)

There are n availabe seats and n students standing in a room. You are given an array seats of length n, where seats[i] is the position of the i^th seat. You are also given the array students of length n, where students[j] is the position of the j^th student.

You may perform the following move any number of times:

  • Increase or decrease the position of the i^th student by 1 (i.e., moving the i^th student from position x to x + 1 or x - 1)

Return the minimum number of moves required to move each student to a seat such that no two students are in the same seat.

Note that there may be multiple seats or students in the same position at the beginning.

Example 1:

Input: seats = [3,1,5], students = [2,7,4]

Output: 4

Explanation: The students are moved as follows:

  • The first student is moved from position 2 to position 1 using 1 move.

  • The second student is moved from position 7 to position 5 using 2 moves.

  • The third student is moved from position 4 to position 3 using 1 move.

In total, 1 + 2 + 1 = 4 moves were used.

Example 2:

Input: seats = [4,1,5,9], students = [1,3,2,6]

Output: 7

Explanation: The students are moved as follows:

  • The first student is not moved.

  • The second student is moved from position 3 to position 4 using 1 move.

  • The third student is moved from position 2 to position 5 using 3 moves.

  • The fourth student is moved from position 6 to position 9 using 3 moves.

In total, 0 + 1 + 3 + 3 = 7 moves were used.

Example 3:

Input: seats = [2,2,6,6], students = [1,3,2,6]

Output: 4

Explanation: Note that there are two seats at position 2 and two seats at position 6.

The students are moved as follows:

  • The first student is moved from position 1 to position 2 using 1 move.

  • The second student is moved from position 3 to position 6 using 3 moves.

  • The third student is not moved.

  • The fourth student is not moved.

In total, 1 + 3 + 0 + 0 = 4 moves were used.

Constraints:

  • n == seats.length == students.length
  • 1 <= n <= 100
  • 1 <= seats[i], students[j] <= 100

submission

impl Solution {
    pub fn min_moves_to_seat(mut seats: Vec<i32>, mut students: Vec<i32>) -> i32 {
        // the idea is sort both array, sum the distance of the seat and student in
        // the same indices
        // for Ai <= Aj and Bi <= Bj
        // |Ai - Bi| + |Aj - Bj| <= |Ai - Bj| + |Aj - Bi|
        seats.sort();
        students.sort();
        seats.into_iter()
            .zip(students)
            .map(|(seat, student)| (seat - student).abs())
            .sum()
    }
}