1184. Distance Between Bus Stops #

题目 #

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

题目大意 #

环形公交路线上有 n 个站，按次序从 0 到 n - 1 进行编号。我们已知每一对相邻公交站之间的距离，distance[i] 表示编号为 i 的车站和编号为 (i + 1) % n 的车站之间的距离。环线上的公交车都可以按顺时针和逆时针的方向行驶。返回乘客从出发点 start 到目的地 destination 之间的最短距离。

提示：

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

解题思路 #

• 给出一个数组，代表的是公交车站每站直接的距离。距离是按照数组下标的顺序给出的，公交车可以按照顺时针行驶，也可以按照逆时针行驶。问行驶的最短距离是多少。
• 按照题意，分别算出顺时针和逆时针的行驶距离，比较两者距离，取出小值就是结果。

代码 #

package leetcode

func distanceBetweenBusStops(distance []int, start int, destination int) int {
	clockwiseDis, counterclockwiseDis, n := 0, 0, len(distance)
	for i := start; i != destination; i = (i + 1) % n {
		clockwiseDis += distance[i]
	}
	for i := destination; i != start; i = (i + 1) % n {
		counterclockwiseDis += distance[i]
	}
	if clockwiseDis < counterclockwiseDis {
		return clockwiseDis
	}
	return counterclockwiseDis
}