1046 Shortest Distance (20 分)

1046 Shortest Distance (20 分)

 

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]), followed by Ninteger distances D​1​​ D​2​​ ⋯ D​N​​, where D​i​​ is the distance between the i-th and the (-st exits, and D​N​​ 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(≤), 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 1.

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

水题，就是一个前缀和就完事。

#include <bits/stdc++.h>
using namespace std;
int n,m;
int an[100005];
int main(){
    cin >> n;
    int sum = 0;
    for(int i = 1; i <= n ; i ++){
        cin >> an[i];
        sum += an[i];
        an[i] += an[i-1];
    }
    cin >> m;
    int xx, yy, x, y;
    for(int i = 0; i < m; i ++){
        cin >> xx >> yy;
        y = max(xx,yy);
        x = min(xx,yy);
        int cnt = an[y-1]-an[x-1];
        int cnt1 = sum - cnt;
        int ans = min(cnt, cnt1);
        cout << ans << endl;
    }
    return 0;
}