1046. Shortest Distance (20)

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 ... D_N, where D_i is the distance between the i-th and the (i+1)-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 (<=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.

5 1 2 4 14 9
3
1 3
2 5
4 1

3
10
7

#include <iostream>
using namespace std;

int main(int argc, const char * argv[]) {
    int n;
    cin >> n;
    int dis[n+1];
    int t, sum = 0;;
    for (int i = 1; i <= n; i++) {
        cin >> t;
        sum += t;
        dis[i] = sum;
    }
    
    int m, l, r;
    cin >> m;
    for (int i = 0; i < m; i++) {
        cin >> l >> r;
        if(l > r) swap(l, r);
        t = dis[r - 1] - dis[l - 1];
        int ans = min(t, sum - t);
        cout << ans << endl;
    }
    
    return 0;
}