1184. Distance Between Bus Stops

A bus has n stops numbered from 0 to n - 1 that form a circle. We know the distance between all pairs of neighboring stops where distance[i] is the distance between the stops number i and (i + 1) % n.

The bus goes along both directions i.e. clockwise and counterclockwise.

Return the shortest distance between the given start and destination stops.

 

Example 1:

Input: distance = [1,2,3,4], start = 0, destination = 1
Output: 1
Explanation: Distance between 0 and 1 is 1 or 9, minimum is 1.

 

Example 2:

Input: distance = [1,2,3,4], start = 0, destination = 2
Output: 3
Explanation: Distance between 0 and 2 is 3 or 7, minimum is 3.

 

Example 3:

Input: distance = [1,2,3,4], start = 0, destination = 3
Output: 4
Explanation: Distance between 0 and 3 is 6 or 4, minimum is 4.

 

Constraints:

  • 1 <= n <= 10^4
  • distance.length == n
  • 0 <= start, destination < n
  • 0 <= distance[i] <= 10^4

Rust Solution

struct Solution;

impl Solution {
    fn distance_between_bus_stops(distance: Vec<i32>, mut start: i32, mut destination: i32) -> i32 {
        let n: usize = distance.len();
        let mut left = 0;
        let mut right = 0;
        if destination < start {
            std::mem::swap(&mut start, &mut destination);
        }
        for i in 0..n {
            let j = start as usize + i;
            if j < destination as usize {
                left += distance[j % n];
            } else {
                right += distance[j % n];
            }
        }
        i32::min(left, right)
    }
}

#[test]
fn test() {
    let distance = vec![1, 2, 3, 4];
    let start = 0;
    let destination = 1;
    let res = 1;
    assert_eq!(
        Solution::distance_between_bus_stops(distance, start, destination),
        res
    );
    let distance = vec![1, 2, 3, 4];
    let start = 0;
    let destination = 1;
    let res = 1;
    assert_eq!(
        Solution::distance_between_bus_stops(distance, start, destination),
        res
    );
    let distance = vec![1, 2, 3, 4];
    let start = 0;
    let destination = 2;
    let res = 3;
    assert_eq!(
        Solution::distance_between_bus_stops(distance, start, destination),
        res
    );
    let distance = vec![1, 2, 3, 4];
    let start = 0;
    let destination = 3;
    let res = 4;
    assert_eq!(
        Solution::distance_between_bus_stops(distance, start, destination),
        res
    );
    let distance = vec![3, 6, 7, 2, 9, 10, 7, 16, 11];
    let start = 6;
    let destination = 2;
    let res = 28;
    assert_eq!(
        Solution::distance_between_bus_stops(distance, start, destination),
        res
    );
}

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