【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,destination = 2
Output: 3
Explanation: Distance between 0 and 2 is 3 or 7,minimum is 3.

?

Example 3:

Input: distance = [1,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)