[Swift]LeetCode1184. 公交站間的距離 | Distance Between Bus Stops

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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

---

環形公交路線上有 n 個站，按次序從 0 到 n - 1 進行編號。咱們已知每一對相鄰公交站之間的距離，distance[i] 表示編號爲 i 的車站和編號爲 (i + 1) % n 的車站之間的距離。

環線上的公交車均可以按順時針和逆時針的方向行駛。

返回乘客從出發點 start 到目的地 destination 之間的最短距離。

 

示例 1：

輸入：distance = [1,2,3,4], start = 0, destination = 1
輸出：1
解釋：公交站 0 和 1 之間的距離是 1 或 9，最小值是 1。

 

示例 2：

輸入：distance = [1,2,3,4], start = 0, destination = 2
輸出：3
解釋：公交站 0 和 2 之間的距離是 3 或 7，最小值是 3。

 

示例 3：

輸入：distance = [1,2,3,4], start = 0, destination = 3
輸出：4
解釋：公交站 0 和 3 之間的距離是 6 或 4，最小值是 4。

 

提示：

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

---

20ms

 1 class Solution {
 2     func distanceBetweenBusStops(_ distance: [Int], _ start: Int, _ destination: Int) -> Int {
 3         var path = [0, 0]
 4         
 5         let lo = min(start, destination)
 6         let hi = max(start, destination)
 7 
 8         
 9         for i in 0 ..< lo {
10             path[0] += distance[i]
11         }
12         for i in lo ..< hi {
13             path[1] += distance[i]
14         }
15         for i in hi ..< distance.count {
16             path[0] += distance[i]
17         }
18         
19         return path[0] < path[1] ? path[0] : path[1]
20     }
21 }

---

Runtime: 24 ms

Memory Usage: 21.3 MB

 1 class Solution {
 2     func distanceBetweenBusStops(_ distance: [Int], _ start: Int, _ destination: Int) -> Int {
 3         var S:Int = 0
 4         var T:Int = 0
 5         var sum:Int = 0
 6         for i in 0..<distance.count
 7         {
 8             if i == start {S=sum}
 9             if i == destination {T=sum}
10             sum += distance[i]
11         }
12         return min(abs(T-S),sum-abs(T-S))
13     }
14 }

---

24ms

 

 1 class Solution {
 2     func distanceBetweenBusStops(_ distance: [Int], _ start: Int, _ destination: Int) -> Int {
 3         var pathA = 0
 4         var pathB = 0
 5         
 6         let lo = start < destination ? start : destination
 7         let hi = start > destination ? start : destination
 8 
 9         for i in 0 ..< lo {
10             pathA += distance[i]
11         }
12         for i in lo ..< hi {
13             pathB += distance[i]
14         }
15         for i in hi ..< distance.count {
16             pathA += distance[i]
17         }
18         
19         return pathA < pathB ? pathA : pathB
20     }
21 }

---

28ms

 1 class Solution {
 2     func distanceBetweenBusStops(_ distance: [Int], _ start: Int, _ destination: Int) -> Int {
 3         var path = [0, 0]
 4         
 5         let lo = min(start, destination)
 6         let hi = max(start, destination)
 7 
 8         
 9         for i in 0 ..< lo {
10             path[0] += distance[i]
11         }
12         for i in lo ..< hi {
13             path[1] += distance[i]
14         }
15         for i in hi ..< distance.count {
16             path[0] += distance[i]
17         }
18         
19         return path[0] < path[1] ? path[0] : path[1]
20     }
21 }

---

32ms

 1 class Solution {
 2     func distanceBetweenBusStops(_ distance: [Int], _ start: Int, _ destination: Int) -> Int {
 3         let a = min(start, destination)
 4     let b = max(start, destination)
 5     let sumDistance = distance.reduce(0) { result, num in result+num }
 6     var sum = 0
 7     for i in a..<b {
 8         sum += distance[i]
 9     }
10     return min(sum, sumDistance-sum)
11     }
12 }