README.md

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

Solutions (Rust)

1. Compare Clockwise with Counterclockwise

impl Solution {
    pub fn distance_between_bus_stops(distance: Vec<i32>, start: i32, destination: i32) -> i32 {
        let n = distance.len() as i32;
        let mut clockwise = 0;
        let mut curr = start;
        while curr != destination {
            clockwise += distance[curr as usize];
            curr += 1;
            curr %= n;
        }

        let mut counterclockwise = 0;
        curr = start;
        while curr != destination {
            curr -= 1;
            curr = (curr + n) % n;
            counterclockwise += distance[curr as usize];
        }
        clockwise.min(counterclockwise)
    }
}

2. Total Distance Subtract Clockwise

impl Solution {
    pub fn distance_between_bus_stops(distance: Vec<i32>, start: i32, destination: i32) -> i32 {
        let n = distance.len() as i32;
        let mut clockwise = 0;
        let mut curr = start;
        while curr != destination {
            clockwise += distance[curr as usize];
            curr += 1;
            curr %= n;
        }

        let total_distance: i32 = distance.iter().sum();
        clockwise.min(total_distance - clockwise)
    }
}

3. Swap Start for Destination

impl Solution {
    pub fn distance_between_bus_stops(distance: Vec<i32>, start: i32, destination: i32) -> i32 {
        let n = distance.len() as i32;
        let mut clockwise = 0;
        let mut curr = start;
        while curr != destination {
            clockwise += distance[curr as usize];
            curr += 1;
            curr %= n;
        }

        let mut counterclockwise = 0;
        curr = destination;
        while curr != start {
            counterclockwise += distance[curr as usize];
            curr += 1;
            curr %= n;
        }
        clockwise.min(counterclockwise)
    }
}