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
公交站间的距离。
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。
来源:力扣(LeetCode)
链接:https://leetcode.cn/problems/distance-between-bus-stops
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题目不难,但是做法很巧妙。题目要求计算的是两点之间的最短距离,最短距离的计算有两种方式,一种是顺时针,一种是逆时针。顺时针很好算,逆时针的算法是整圈的距离 - 顺时针的距离。
时间O(n)
空间O(1)
Java实现
1 class Solution { 2 public int distanceBetweenBusStops(int[] distance, int start, int destination) { 3 int total = 0; 4 for (int dis : distance) { 5 total += dis; 6 } 7 8 if (start > destination) { 9 int temp = start; 10 start = destination; 11 destination = temp; 12 } 13 int dis1 = 0; 14 for (int i = start; i < destination; i++) { 15 dis1 += distance[i]; 16 } 17 return Math.min(dis1, total - dis1); 18 } 19 }