【leetcode】1184. Distance Between Bus Stops

题目如下：

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

解题思路：因为公交车的路线是一个环形，所以A到B的最短路径不是顺时针方向就是逆时针方向，比较哪个距离小即可。

代码如下：

class Solution(object):
    def distanceBetweenBusStops(self, distance, start, destination):
        """
        :type distance: List[int]
        :type start: int
        :type destination: int
        :rtype: int
        """
        val = [0]
        amount = 0
        for i in distance:
            amount += i
            val.append(amount)
        dis = abs(val[destination] - val[start])
        return min(dis,amount-dis)