题解

#include <bits/stdc++.h>
using namespace std;
int n,a[114514],ans = 0;
int main(){
    cin >> n;
    for(int i = 0;i < n;i ++){
        cin >> a[i];
        ans += a[i];
    }
    int son1 = a[0],son2 = a[n - 1];
    int l = 0,r = n - 1;
    int cur = ans - son1 - son2;
    if(son1 == son2) ans = cur;
    while(l < r){
        if(son1 == son2) {
            ans = cur;
            l ++;
            son1 += a[l];
            cur -= a[l];
        }
        while(l < r && son1 < son2){
            l ++;
            son1 += a[l];
            cur -= a[l];
        }
        while(l < r && son1 > son2){
            r --;
            son2 += a[r];
            cur -= a[r];
        }
    }
    cout << ans << endl;
    return 0;
}