PAT Advanced 1046 Shortest Distance

#include<stdio.h>
#include<vector>
using namespace std;

int main(){
    int n;
    scanf("%d",&n);
    vector<int> dis(n);
    int sum=0;
    vector<int> porder(n);
    vector<int> rorder(n);
    for(int i=0;i<n;i++){
        porder[i] = sum;
        int v;
        scanf("%d",&v);
        sum+=v;
        dis[i]=v;
    }
    int rsum=0;
    for(int i=n-1;i>=0;i--){
        rsum+=dis[i];
        rorder[i]=rsum;
    }
    int m;
    scanf("%d",&m);
    for(int i=0;i<m;i++){
        int st,ed;
        scanf("%d %d",&st,&ed);
        int little = st<ed?st:ed;
        int large = st<ed?ed:st;
        int partSum= porder[little-1] + rorder[large-1];
        int res = partSum<sum-partSum?partSum:sum-partSum;
        // printf("sum:%d psum:%d sum-psum:%d res:%d\n",sum,psum,sum-psum,res);
        printf("%d\n",res);
    }
}