1046. Shortest Distance (20)-PAT甲级真题

The task is really simple: given N exits on a highway which forms a simple cycle, you are supposed to tell the shortest distance between any pair of exits.

Input Specification:

Each input file contains one test case. For each case, the first line contains an integer N (in [3, 105]), followed by N integer distances D1 D2 … DN, where Di is the distance between the i-th and the (i+1)-st exits, and DN is between the N-th and the 1st exits. All the numbers in a line are separated by a space. The second line gives a positive integer M (<=104), with M lines follow, each contains a pair of exit numbers, provided that the exits are numbered from 1 to N. It is guaranteed that the total round trip distance is no more than 107.

Output Specification:

For each test case, print your results in M lines, each contains the shortest distance between the corresponding given pair of exits.

Sample Input:
5 1 2 4 14 9
3
1 3
2 5
4 1
Sample Output:
3
10
7

分析:简单模拟。所有结点连起来会形成一个环形,dis[i]存储第1个结点到第i个结点的下一个结点的距离,sum保存整个路径一圈的总和值。求得结果就是dis[right – 1] – dis[left – 1]和 sum – dis[right – 1] – dis[left – 1]中较小的那一个~~
注意:可能left和right的顺序颠倒了,这时候要把left和right的值交换~